Zoological Philosophy

Jean-Baptiste Pierre Antoine de Monet,Chevalier de Lamarck

Translated by Ian Johnston

This file edited by Eli Vieira

DISCLAIMER AND SHORT PROLOGUE

This translation has been prepared by Ian Johnston, of Malaspina University-College, Nanaimo, BC, Canada. All sections listed below are in the public domain, and may be used by anyone, in whole or in part, without permission and without charge, provided the source is acknowledged, released September 1999. For comments and suggestions please contact johnstoi@mala.bc.ca. I would particularly welcome suggestions to improve or correct the translation. For a brief note on the translation click here.

Ian Johnston

I felt free to license this ebook in Creative Commons 2.5, which agrees with the above statement by the translator. Check out the original source.

Jean-Baptiste Lamarck, the coiner of the term Biology to describe a novel science, has played a unique and important role in it by perceiving that the living beings where not immutable. He followed the tradition of Georges-Louis Leclerc (Comte de Buffon) and built on works by other naturalists such as Louis-Jean-Marie Daubenton and Georges Cuvier. Late in his life, embracing the new concept of biological evolution, Lamarck was in himself a sample of a great scientific shift to come in the nineteenth century. His change of mind was the foresight of the change about to happen in the conceptions of naturalists about the origin of species. The bicentennial of “Philosophie Zoologique” should be as celebrated as the bicentennial of his famous and rebel 'disciple', Charles Darwin, who, contrary to modern beliefs, shared many of Lamarck's views 150 years ago.

Eli Vieira, march 11th 2009

ZOOLOGICAL PHILOSOPHYOR

EXPOSITIONOf the considerations relevant to the natural history of animals; to the diversity of their organic structure and of the faculties which they derive from it; to the physical causes sustaining life in them and producing the movements which they carry out; finally, to those causes which produce feeling in some and intelligence in others endowed with it.

By J.-B.-P.-A. LAMARCK,Professor of Zoology at the Museum of Natural History, Member of the Institute of France and the Legion of Honour, the Philomatique Society, the Naturalists' Society of Moscow, Corresponding Member of the Royal Academy of Sciences of Munich, the Society of the Friends of Nature of Berlin, the Medical Emulation Society of Bordeaux, the Society of Agriculture, Sciences and Arts of Strasbourg, the Society of Agriculture of the Department of the Oise, the Society of Agriculture of Lyon, Free Associate of the Society of Pharmacists of Paris, etc.

PARIS 1809

VOLUME ONE

Table of contents

Foreword .......................................................................................................... 5

Preliminary Discourse ..................................................................................... 19 PART ONEConsiderations of the Natural History of Animals, Their Characteristics, Their Interrelationships, Their Organic Structure, Their Distribution, Their Classification and Their Species Chapter One .................................................................................................... 32 On the Role of Art in the Productions of Nature Chapter Two ................................................................................................... 48 The Importance of Considering Affinities Chapter Three ................................................................................................. 59 Concerning Speciation in Living Things and The Idea We Should Attach to This Word Chapter Four ................................................................................................... 81 General Observations on Animals Chapter Five ................................................................................................... 96 On the Present State of the Distribution and Classification of Animals Chapter Six ................................................................................................... 118 The Degradation and Simplification in Organic Structure from One Extreme to the Other of the Chain of Animal Life, from the Most Complex to the Simplest Chapter Seven ............................................................................................... 182 Concerning the Influence of Circumstances on the Actions and Habits of Animals, and the Influence of the Actions and Habits of these Living Bodies As Causes Which Modify Their Organic Structure and Their Parts Chapter Eight ................................................................................................ 221 Concerning the Natural Order of Animals and the Arrangement Which Must Have Led to Their General Distribution to Make it Conform to the Very Order of Nature

Foreword

My teaching experience has made me sense how much a Philosophical Zoology, that is, a body of precepts relevant to the study of animals and even applicable to other parts of the natural sciences would be useful now, when for the past thirty years our knowledge of the facts of zoology has made considerable progress.

Consequently, I attempted to sketch an outline of this philosophy for use in my classes, to make it easier for my students to understand me. At that time I had no other purpose.

But to reach a determination of these principles and, by following them, to establish precepts which might guide our study, I had consider the organic structure of the different animals we know about, to think through the particular differences which this organic structure presents in the members of each family, each order, and especially each class, to compare the faculties which these animals have derived from it according to their level of complexity in each race, and finally to recognize the most universal phenomena which this structure presents in the main examples. I was successively led to include considerations of the most important scientific interest and to examine the most difficult questions in zoology.

In fact, how could I explore the remarkable degradation found in the organic structure of animals, as one goes through the series from the most perfect among them

right down to the most imperfect, without looking into what could control such a firm and remarkable fact, something confirmed for me by so many proofs? Must I not think that nature had produced the different bodies endowed with life in succession, proceeding from the simplest to the most highly organized, since, as we go up the animal scale from the most imperfect right up to the most perfect, the organism's organic structure is developed and gradually becomes more complex in an extremely remarkable way?

This idea, moreover, acquired in my eyes the most conclusive evidence when I recognized that the simplest of all organic structures displays no specialized organs whatever, that the body which possesses such a structure really has no special faculty, but only those appropriate to all living bodies, and that as nature comes to create, one after the other, the different specialized organs and also to increase more and more the complexity of organic structures, the animals acquire different special faculties according to the degree of that complexity, faculties which, in the most perfect among them, are numerous and very strongly marked.

I could not decline to pay attention to these matters. That soon led me to examine the question about what really constitutes life and what conditions this natural phenomenon requires in order to appear and to be able to remain in a body. My reluctance to pursue this research was even less because I was then convinced that in the simplest of all structures one could find, in a unique way, the appropriate methods of coming up with the solution to a problem apparently so difficult, because that study alone presented the full array of conditions necessary to the presence of life without anything extra which could mislead.

The complete conditions necessary for the existence of life are found in the least complex organic structure, but also reduced to their simplest terms. It was a matter of knowing how this structure, whatever the causes of change, was able to lead to other less simple organic structures and to give rise to the gradually more complicated arrangements observed in the range of the scale of animal life. Using the two following ideas, to which observation led me, I believed I saw the solution to the problem which preoccupied me.

First, there is considerable factual evidence proving that the sustained use of an organ leads to its development, strengthens it, and even makes it grow larger, while a lack of use, once it becomes habitual, is harmful to an organ's development, makes it deteriorate, gradually diminishes it, and finishes by making it disappear, if this lack of use continues for a long time in all the individuals which appear later through reproduction. From this we understand that when a change in the circumstances compels the individuals of an animal race to change their habitual behaviour, the less used organs little by little waste away, while those which are used more develop better and acquire a strength and dimensions proportional to the use which these individuals routinely make of them.

Secondly, reflecting on the power of movement of fluids in the very supple parts which contain them, I was soon convinced that to the extent that the fluids of an organic body increase their rapidity of movement, they modify the cellular tissue in which they move, open up passages there, form various canals, and finally create different organs, depending on the state of the organic complexity in which they are found.

By following these two considerations, I accepted as certain the fact that the movement of fluids in the interior of animals, a movement which is progressively accelerated with the increasing complexity in organic structure, and the influence of new circumstances, to the extent that animals are exposed to them as they move out into all habitable areas, were the two general causes which have led the different animals to the condition where we see them now.

In this work, I did not limit myself to expanding on the conditions essential to the existence of life in simplest organisms, any more than to the causes which have given rise to the growing complexity of animal structures, from the most imperfect right up to the most perfect. But believing that I could glimpse the possibility of recognizing the physical causes of feeling, which so many animals enjoy the use of, I did not hesitate to make that my concern.

In fact, because I was persuaded that it was not just any material whatever which could inherently have the faculty of feeling and because I thought that feeling itself is only a phenomenon resulting from the functioning of an organic system capable of producing it, I sought out what might be the organic mechanism which could give rise to this admirable phenomenon, and I believe I have grasped it.

In collecting the most reliable observations on this subject, I had occasion to recognize that, for the production of feeling, the nervous system had to be already very complex, just as it had to be much more complex still to give rise to the phenomena of intelligence.

Following these observations, I was persuaded that the nervous system, in its least perfect condition, like that in the

imperfect animals which first begin to possess one, is only, in this condition, for the excitation of muscular movement and that then it does not have the capacity to produce feeling. In this condition, it offers only medullary ganglia from which threads go out and does not show evidence of either a longitudinal marrow with ganglia or a spinal chord or a brain. In a more advanced state of complexity, the nervous system shows a principal medullary mass, in an elongated form, consisting of either a longitudinal marrow or a spinal chord, whose anterior extremity gives evidence of a brain which contains the area of sensations and effectively gives birth to the nerves of particular senses, at least to some of them. Thus, the animals which possess a system in this condition enjoy the faculty of feeling.

Then I tried to determine the mechanism by which a sensation takes place, and I showed that it produces only a perception for the individual who lacks an organ for intelligence, so that it cannot give that individual any sort of idea. I showed that in spite of the possession of this special organ, this sensation would again produce only a perception, every time it is not specially noticed.

In truth, I have not decided on the question of understanding how, in this mechanism, the sensation takes place, whether by an emission of the nervous fluid leaving the affected point or by a simple communication of movement in the same fluid. However, since the duration of certain sensations is relative to the stimuli which cause them, I am leaning toward this second view.

My observations would not have provided any satisfactory illumination on these subjects under discussion, if

I had not managed to recognize and been able to prove that feeling and irritability are two very different organic phenomena, that they in no way have a common source, as people have believed, and finally that the first of these phenomena constitutes a specific faculty in certain animals, which demands a special system of organs to be able to work, while the second, which does not require any specific organs, is exclusively the property of all animal organisms.

Moreover, so long as these two phenomena are confused in their source and their effects, it will be easy and common for people to be wrong in the explanations which they try to provide concerning the causes of most of the phenomena in animals' organic structure. This will be so above all when, wishing to conduct research into the principle of feeling and movement and finally to locate the seat of this principle in the animals which possess these faculties, people undertake experiments to find them.

For example, after having decapitated certain very young animals or having cut the spinal column between the occiput and the first vertebra or having pushed a stylus in there, people have taken the various movements brought about by the inhalation of air in the lung as proof of the renewal of feeling with the aid of artificial respiration; whereas, these effects are due, in some cases, only to the not-yet-extinguished irritability (for we know that it still lasts for some time after the death of the individual), and, in other cases, only to some muscular movements which the inhalation of air can still stimulate, when the spinal column has not been destroyed by the introduction of a long stylus along the total length of the spinal canal.

If I had not recognized that the organic action which gives rise to the movement of parts is entirely independent of that which produces feeling, although the influence of the nervous system is necessary in both cases, and if I had not noticed that I can set in motion several of my muscles without registering any sensation and that I can receive a sensation without any subsequent muscular movement, I also could have taken the excited movements in a young animal which had been decapitated or whose brain had been removed for signs of feeling. And I would have been wrong.

I think that if the individual, by his nature or otherwise, is incapable of accounting for a sensation which he is undergoing and if he does not, by some cries, attest to the pain which he is being made to experience, we have no other certain sign of recognizing that he is receiving this sensation, when we know that the organic system which gives him the faculty of feeling is not destroyed and remains inherently intact: excited muscular movements in themselves do not prove an act of feeling.

Having set my thoughts on these interesting matters, I considered inner feeling, that is, the feeling of being alive, which only animals enjoying the faculty of feeling possess. I collected the known facts concerning this matter, as well as my own observations, and I was soon convinced that this inner feeling constituted a power essential to take into account.

In fact, nothing seems to me to be more important than the feeling under discussion, considered in man and in the animals possessing a nervous system capable of producing it, a feeling which the physical and moral needs have the

capacity of arousing and which becomes the source from which movements and actions derive their active powers. No one I know has paid attention to this, so that this gap concerning the knowledge of one of the most powerful causes of the main phenomena in animal organisms undermines everything that can be imagined to explain these phenomena. However, we have a sort of presentiment of this inner power, when we speak of agitations which we experience in ourselves in thousands of circumstances; for the word emotion, which I did not make up, is often enough uttered in conversation to express the remarkable facts which this power refers to. When I considered that the interior feeling was capable of being moved by different causes and then that it could constitute a power capable of initiating actions, I was in some way struck by the multitude of known facts which confirm the basis or the reality of this power; and the difficulties which had long held me back concerning the causes inciting action seemed to me entirely removed.

In assuming that I had so fortunately grasped a truth in the idea of attributing to interior feeling in the animals endowed with it the power which produces their movements, I had removed only a part of the problematic difficulties in this research. For it is evident that not all the known animals either possess or are capable of possessing a nervous system, that, consequently, not all of them enjoy the interior feeling which we are discussing, and that in those who lack such a system the movements which we see them carry out must have another origin.

At this point, when I considered that without exterior stimuli vegetable life would not exist, not being capable of sustaining itself, I soon realized that a large number of animals must find themselves in the same situation. And, as I had frequent occasion to observe that in order to arrive at the same goal nature varies its means, when necessary, I had no further doubts in this matter.

Thus, I think that the very imperfect animals lacking a nervous system live only with the help of the stimuli they receive from outside. That is to say, subtle constantly moving fluids contained in the environmental surroundings move continuously into these organic bodies and there sustain life to the extent that the condition of these bodies enables them to do so. Now, this idea, which I have so often considered, which so many facts appear to me to confirm, which none of those known to me seems to deny, and finally which vegetative life seems to me manifestly to confirm, this idea, I say, was for me a single ray of light which made me see the principal cause which maintains movements and life in organic bodies and to which animals owe everything which gives them life.

By bringing together this notion with the two preceding ones, that is, combining the ideas about the movement of fluids in the interior of animals and the one about the consequences of a sustained change in the circumstances and habits of these creatures, I was able to grasp the central thread which links up the numerous causes of the phenomena which the developments and the diversity of animal organic structure present to us. Soon I saw the importance of this method in nature, which consists in preserving in newly produced individuals all the things which

the effects of life and environmental influences have produced in the organic structure of those bringing these individuals into existence.

Now, having noticed that animal movements are never communicated but always stimulated, I recognized that nature, obliged at first to borrow from the environmental surroundings the stimulating power for vital movements and actions in imperfect animals, was capable, when creating animals of increasing complexity, of bringing this power right inside these creatures, and that finally she succeeded in putting this same power at the disposal of the individual.

Such are the principal subjects which I have tried to set out and develop in this work.

Thus, this Philosophical Zoology presents the results of my studies of animals, their general and particular characteristics, their organic structure, the causes of their developments and diversity, and the faculties they have acquired from it. To write this work, I have used the major materials which I assembled for a projected work on living bodies, under the title of Biology, a book which, so far as I am concerned, will remain unwritten.

The facts which I cite are very numerous and reliable, and the conclusions which I have derived from them seem to me appropriate and necessary, so that I am convinced that it will be difficult to replace them with better ones.

However, the number of new ideas revealed in this work must naturally, as soon as they are first stated, unfavorably impress the reader, by the sole ascendancy which universally accepted ideas always have over new ones which tend to cast them aside. Now, since this power of old ideas

over those appearing for the first time favours this prejudice, especially when the matter is the least bit interesting, the result is that whatever the difficulties may be in discovering new truths through the study of nature, the difficulties of getting them accepted are much greater still.

These difficulties, arising for different reasons, are basically more of a help than a hindrance for the state of general knowledge. For because the rigour which makes it difficult to get newly presented ideas accepted as truths, a multitude of odd ideas, more or less specious and without foundation, no sooner appear than they quickly fall into oblivion. Sometimes, however, some excellent opinions and solid ideas are, for the same reasons, rejected or neglected. But it is better that a truth, once perceived, fight a long time without obtaining the attention it deserves, than that everything produced by men's keen imaginations be easily accepted.

The more I think about this subject, particularly about the numerous causes which can affect our judgments, the more I am persuaded that, except for physical and moral facts1, which no one can call into question, all the rest is nothing but opinion or speculation. We know that one can always oppose one set of reasons by others. Thus, although it may be evident that there are great differences in the persuasiveness, probability, and even the worth among the

1 I call moral facts the mathematical truths, that is to say, the results of calculations, whether of quantities, forces, or measurements, because it is through intelligence and not by our senses that these facts are known to us. Now, these moral facts are at one and the same time positive truths, as are facts relative to the existence of bodies which we can observe, as well as others which concern these bodies.

various opinions of men, it seems to me that we would be wrong to blame those who refuse to accept our views.

Must we not recognize as grounded the most universally accepted opinions? But experience demonstrates well enough that the individuals who have the most highly developed intelligence and who combine the most insights make up at all times an extremely small minority. There is no way to deny that. Where matters of knowledge are concerned, the authorities should appreciate the point, and not just judge by numbers, although in truth such appreciation may be very difficult.

However, according to the numerous and rigorous conditions which a judgment requires for it to be a good one, it is still not certain that the judgment of the individuals whom opinion transforms into authorities is perfectly justified concerning the objects on which it delivers its opinion.

There are thus no really reliable truths for human beings, that is to say, things on which they can firmly count, except the facts which they can observe (not the consequences which they derive from them), the existence of nature which presents these facts, as well as the materials to obtain them, and finally the laws which regulate the movements and the changes of nature's parts. Beyond that, everything is uncertain, although some consequences, theories, opinions, and so on are much more probable than others.

Since it is not possible to count on any chain of pure reasoning, on any conclusions, on any theory, the authors of these intellectual pursuits cannot be certain that they have

used there the true elements which must have given rise to it, that they have not allowed in any elements except those and have not neglected any. There is nothing reliable for us except the existence of bodies which can affect our senses, those real qualities which belong to them, and finally those physical and moral facts which we can know. Thus, the ideas, the chains of reasoning, and the explanations which one finds revealed in this work must be considered only simple opinions which I propose, with the intention of indicating what appears to me might be the case and what could have really taken place.

Whatever the case may be, in delivering myself of the observations which have given rise to the considerations revealed in this work, I have obtained the pleasures that their resemblance to truths enabled me to experience, as well as the reward for the fatigue attendant on my studies and meditations. In publishing these results which I have deduced from these observations, I intend to invite insightful people who love the study of nature to follow and verify them, drawing from them in their turn the conclusions which they judge acceptable.

Since this way seems to me the only one which can lead to knowledge of the truth or of what comes closest to it and since it is evident that this knowledge is more advantageous to us than the error which we can put in its place, I cannot doubt that this is the way we must follow.

One will be able to see that the exposition in the second and especially the third parts of this work gave me particular pleasure and that they greatly stimulated by interest. However, the principles relevant to natural history

which I concern myself with in the first part must at least be considered as the things potentially most useful to science, these principles being, in general, most closely connected to what people have thought up to the present day.

I had the resources to extend this work considerably, by presenting all the developments for each point which the interesting materials it includes could allow. But I have preferred to limit myself to the explanations strictly necessary for a sufficient understanding my observations. In this way, I have saved my readers time, without risking that they will not be able to understand me.

I shall have achieved my proposed purpose if those who love the natural sciences find in this work some views and principles useful to them, if the observations which I reveal here and which are my own are confirmed or approved by those who have had the opportunity to busy themselves with the same things, and if the ideas which are in a position to do so, whatever they are, can advance our understanding or put us on the road to reach some unknown truths.

Preliminary Discourse

Observe nature. Study her productions. Carry out research into the general and particular interconnections which she has impressed on their characteristics. Finally try to grasp the order which she has brought into being everywhere, as well as her progress, her laws, and the infinitely varied ways which she uses to give rise to this order--that is, in my view, to put oneself in a position to acquire the only reliable knowledge at our disposal (the only one, moreover, which can be truly useful to us) and at the same time to gain the sweetest pleasures, those most appropriate to assuage the inevitable pains of life.

In fact, what is more interesting in the observation of nature than the study of the animals, than thinking about the connections between their structure and that of human beings, about the power which their habits, ways of life, climates, and environments have to modify their organs, faculties, their characteristics, than an analysis of the different structural systems which we see among them and according to which we determine the relationships, some important, others less so, which fix the rank of each one in the natural order. Finally, what is more interesting than the general arrangement which we establish for these animals, taking into account the greater or lesser complexity in their structures, an arrangement which can lead to an understanding of the very order which nature has followed in bringing each species into existence?

Certainly one cannot deny that that all these questions and several others as well which the study of animals necessarily leads to are of great interest to anyone who loves nature and seeks the truth in everything.

What is odd is that the most important phenomena to consider have only been available for our reflections since the time when people concerned themselves mainly with the study of the least perfect animals and when research into the different complexities in the structures of these animals became the main basis of their study.

It is no less odd to be forced to acknowledge that it was almost always from the sustained examination of the smallest objects which nature presents to us and from the most apparently minute considerations that we have obtained the most important knowledge for discovering nature's laws and methods and for determining her progress. This truth, already confirmed by many remarkable facts, will receive new evidence in the matters revealed in this work, and we must be convinced more than ever that, so far as the study of nature is concerned, no object whatsoever is unworthy of attention.

The purpose of the study of animals is not exclusively to understand their different races and to determine all the distinctions among them by establishing their special characteristics. It is also to reach an understanding of the origin of the faculties which they enjoy and of the causes which brought them into existence and now maintain their lives and, finally, the causes of that remarkable progression which they display in their form and structure and in the number as well as in the development of their faculties.

At their source, the physical and the moral are, without doubt, only one and the same thing. And by studying the organic structure of the different orders of known animals, we can provide the most impressive evidence for this truth. Now, as the products of this source are effects and since these effects, at first distinguished from each other with difficulty, have subsequently separated into clearly distinct orders, these two groups of effects, the physical and the moral, considered in their most important distinction, have appeared to us and still appear to plenty of people to have nothing in common between them.

However, the influence of the physical upon the moral has already been recognized.2 But it seems to me that we have not yet given sufficient attention to the influence of the moral on the physical itself. Now, these two orders of things, which have a common source, react upon each other, above all when they appear the most separate, and we have nowadays the means to prove that they change themselves in one way or another in their variations.

It strikes me that we have gone wrong in our efforts to demonstrate the common origin of the two orders of effects, which, when most distinct from each other, make up what we call the physical and the moral. We have chosen a road opposite to that which must be followed.

In fact, people started to study these two sorts of things, apparently so distinct, in man himself, where the organic structure, having reached the limit of its design and perfectibility, displays the greatest complexities in the causes

2 See the interesting work of M. Cabanis, entitled Rapport du physique et du moral de l'Homme.

of the phenomena of life, of feeling, and finally of the faculties he enjoys. In man, thus, it is most difficult to grasp the source of so many phenomena.

After having thoroughly studied the organic structures of man, as people have done, rather than fussing about with research into the very causes of life in this structure, the causes of physical and moral sensation, in a word, of the lofty faculties he possess, we then had to try hard to understand the structure of other animals, to consider the differences which exist among them in this respect, as well as the connections which occur between the faculties which are appropriate to them and the organic structure which they have been given.

If these different things had been compared with each other and with what was known concerning man, and if people had taken into account, from the organic structure of the simplest animals right up to that of man, the most complex and the most perfect, the progression manifest in the complexity of the organic structure as well as the successive acquisition of different specialized organs, and consequently of so many new faculties which the new organs bring, then people could have seen how needs, at first reduced to nothing, but then gradually increasing in number, have led to a tendency for actions appropriate to satisfy those needs. They could have seen how, once these actions became habitual and energetic, they brought about the development of organs which carry them out; and how the force which stimulates organic movements can, in the most imperfect animals, be located outside of them and nevertheless animate them, how later this force was moved and fixed in the animal itself, and finally, how this force has there become the source of sensibility and at last of intelligent action.

I will add that if people had followed this method, then they could not have considered feeling as the universal and immediate cause of organic movements and could not have said that life is a series of movements carried out by virtue of sensations received by the different organs or, alternatively, that all the vital movements are the product of impressions received by the sensing parts. Rapp. Du phys. Et du moral de l'Homme, p. 38 to 39, and 85.

This cause would appear to be, up to a certain point, based upon a consideration of the most perfect animals; but it was also relevant to all the bodies which enjoyed life: they all possessed the faculty of feeling. Now, people did not know how to show us that plant life is in the same condition; people did not know even how to prove that this was the case with all the known animals.

I do not acknowledge at all the assumption of such an allegedly universal cause for the real march of nature. In creating life, she did not start suddenly by establishing such a high faculty as that of feeling. She did not have the means to bring such a faculty into existence in the imperfect creatures of the first classes in the animal kingdom.

With respect to the bodies which enjoy life, nature made everything gradually and successively; there is no longer any possible doubt about that.

In fact, among the different things which I propose to explain in this work, I will try to reveal, by referring throughout to known facts, that in making animals' organic structures increasingly complex, nature has progressively created different specialized organs as well as the faculties which the animals enjoy.

For a long time it has been thought that there existed a sort of ladder or graduated chain among the bodies endowed with life. Bonnet developed this view, but he did not prove it by facts derived from organic structure itself; that, however, was necessary, especially in relation to animals. He could not do it, because at the time he lived people did not yet have the means.

As one studies animals of all the classes, there are plenty of things to see other than the growing complexity in animal organic structure. The production of causal circumstances leading to new needs, those needs giving rise to actions, those repeated actions creating the habits and inclinations, the results of increased or diminished use of some organ or other, the means which nature uses to preserve and improve everything acquired in the structure, and so on and so on--these are things of the highest importance for rational philosophy

But this study of animals, especially of the less perfect ones, was for a long time neglected; we were so far from suspecting the great interest which it could provide. And what has been started in this respect is still so recent, that in pursuing it, we have reason to expect many new insights.

When people started truly to cultivate natural history and each kingdom attracted the attention of naturalists, those who directed their research into the animal kingdom studied mainly the vertebrates, i.e., mammals, birds, reptiles, and finally fish. In these classes of animals, since the species are generally larger, have more developed parts and faculties, and are more easily characterized, they appeared to offer more

interesting material to study than those which belong to the division of invertebrate animals.

In fact, the extremely small size of most of the invertebrates, their limited faculties, and the fact that their organs have a much more distant relationship to human ones than the ones we observe among the more perfect animals--these made them, in some ways, commonly despised and, right up to our time, gave them only a very luke-warm interest for the majority of naturalists.

However, we are beginning to retreat from this prejudice harmful to the advancement of our knowledge, for in the past few years, when these remarkable animals have been examined attentively, we have been forced to recognize that the study of them must be considered one of the most interesting for the naturalist and the philosopher, because it sheds light onto a number of problems relevant to natural history and animal physics, insight which it would be difficult to obtain in any other way.

When I was given the task in the Museum of Natural History of making displays of animals which I call invertebrates (because of their lack of a vertebral column), my research on these numerous animals, the observations and facts which I collected concerning them, and finally the insights which I borrowed from comparative anatomy with respect to them soon gave me the keenest idea of the interest which a study of them inspires.

In fact, the study of invertebrates must be of special interest to the naturalist. First, the species of these animals are much more numerous in nature than the vertebrate species. Second, since they are more numerous, they are necessarily

more varied. Third, the variations in their organic structure are much greater, more clear cut, and more peculiar. Finally, the order which nature uses to form in succession the different animal organs is much better expressed in the mutations which these organs undergo in the invertebrates and makes the study of them much more appropriate for getting us to see the very origin of organic structure, as well as the reason for its complexity and development. All the issues revealed by the more perfect animals, like the vertebrates, could not achieve this.

Once I was struck with these truths, I felt that, in order to make them comprehensible to my students, rather than burying myself right from the start in details about particular things, I must, above all, present to them the general truths relevant to all the animals, to show them the entire collection, along with the essential considerations pertinent to such a collection. I proposed after that to grasp the principal groups which seemed to divide up this collection in order to establish comparisons among them and to make the students better understand each one separately.

In fact, the true way to arrive at a full understanding of something, even in its smallest details, is to start by envisaging it in its entirety, by an initial examination, whether of its mass, its extent, or the collection of parts which make it up, by researching what its nature and origin are, what are its connections to other known things, in a word, by considering it from all the points of view which can illuminate for us all the general truths which concern that thing. Later one divides the object under investigation into its principal parts in order to study them and consider them separately in connection with all those interrelationships

which can tell us things about them; and continuing in this way to divide and sub-divide these parts examined in succession, we go right down to the smallest, whose particular details we study, not overlooking the least details. When all this research is finished, one tries to deduce from it the consequences, and little by little the philosophy of science establishes, corrects, and perfects itself.

Only by this path can human intelligence acquire the most far reaching, most reliable, and most fully coordinated knowledge in any science whatsoever. And it is solely by this method of analysis that all sciences make true progress and that the things that they deal with are not confused and can be perfectly understood.

Unfortunately, we are not sufficiently in the habit of following this method in studying natural history. The acknowledged necessity for good observation of particular objects has given birth to the habit of limiting oneself to the consideration of these things and of their smallest details, in such a way that for the majority of naturalists that has become the main subject of study. This, however, would really slow down the natural sciences if we persist in not seeing anything in the objects observed except their shape, dimensions, external parts, even the smallest, their colour, and so on and if those who undertake such a study refuse to rise up to some loftier considerations, for example, to seek out the nature of these things which they are busy with, the causes of the modifications or the variations to which these things are all subject, the interrelationships of these same things amongst themselves and with all the others which we know about, and so on.

Because we have not followed sufficiently the method which I have just mentioned, we notice such a divergence in what is taught in these matters, whether in the works of natural history or elsewhere, and those who specialize in the study of species do not grasp, except with great difficulty, the general interconnections among things, not perceiving anything of the true plan of nature and recognizing hardly any of her laws.

Convinced, on the one hand, that we must not follow a method which restricts and limits our ideas in such a way, and on the other hand finding myself needing to publish a new edition of my System of Invertebrate Animals, because the rapid progress in comparative anatomy, the new discoveries by zoologists, and my own observations gave me the means to improve this work, I thought I should collect in a single work under the title of Zoological Philosophy the following: (1) the general principals relevant to the study of the animal kingdom, (2) the essential observed facts which one needs to take into account in this study, (3) the considerations which govern the non-arbitrary distribution of animals and their most suitable classification, and finally (4) the most important consequences which one infers naturally from the observations of collected facts and which are the basis of the true philosophy of science.

The Zoological Philosophy in question is nothing other than a new edition, put on a fresh basis, corrected, and much enlarged of my work entitled Research into Living Organisms. It is divided into three main parts, and each of these parts is divided into different chapters.

Thus, in the first part, which should present the essential observed facts and the general principles of the natural sciences, to begin with I am going to consider what I call the artistic parts of the sciences under review, the importance of taking into account the interconnections, and the idea that one must form of what is called a species among living bodies. Then, after having developed the general truths relevant to animals, I will lay out, on the one hand, proofs of the degradation in the organic structure governing the animal scale from one extremity to the other, the most perfect animals standing at the front part of this scale and, on the other hand, I will show the influence of circumstances and habits on animal organs, how these are the root causes which favour or prevent organic development. I will end this section by considering the natural order of animals and by revealing their distribution and their most suitable classification.

In the second part, I will set forth my ideas on the order and the condition of things which create the essence of animal life, and I will indicate the essential conditions for the existence of this admirable phenomenon of nature. Then I will attempt to determine the causal stimulus of organic movements, those of orgasm and of irritability, the properties of the cellular tissue, the unique circumstance in which spontaneous generation can taken place, the manifest consequences of living acts, and so on.

Finally, the third part will present my opinion on the physical causes of feeling, on the power of action, and the acts of intelligence in certain animals.

I will deal there with the following: (1) the origin and the formation of the nervous system; (2) the nervous fluid

which can be known only indirectly, but whose existence is attested to by phenomena which it alone can produce; (3) physical sensibility and the mechanism of sensations; (4) the force producing animal movements and actions; (5) the source of will or the faculty of willing; (6) ideas and their different orders; and finally (7) some particular acts of understanding, like attention, thoughts, imagination, memory, and so on.

The topics revealed in the second and the third part include, without doubt, some subjects very difficult to examine and even some apparently insoluble questions. But they hold so much interest that some attempts to deal with them could be advantageous, whether pointing out some unperceived truths or opening the way which possible leading to them.

First PartConsiderations of the Natural History of Animals, Their Characteristics, Their Interrelationships, Their Organic Structure, Their Distribution, Their Classification and Their Species

Chapter One

Concerning the Role of Art in the Productions of Nature

Throughout nature, where man works diligently to acquire knowledge, he is forced to use particular methods, as follows: (1) to arrange in an orderly way the infinitely numerous and varied objects which he examines; (2) to make clear distinctions among the immense multitude of these things, whether the groups of those in which he is at all interested in learning about, or each particular one of them; (3) finally, to communicate and hand down to his colleagues everything which he has learned, noticed, and thought about concerning them. Now, the means which he uses in such views of nature constitute what I call the artistic parts in the natural sciences, parts which one must be careful not to confuse with the laws and the acts of nature herself.

Just as it is necessary to distinguish in the natural sciences between what belongs to art and what is a feature of nature, so also in these sciences one must distinguish between two very different interests which bring us an understanding of the natural productions which we can observe.

The first is an interest which I call essentially economic, because it derives its source from the economic and pleasurable needs of human beings relative to the productions of nature which they wish to make serve their

own ends. From this point of view, a person is interested only in those things which he thinks can be useful to him.

The other, very different from the first, is that philosophical interest which makes us want to know nature herself in each of her productions, in order to grasp her progress, laws, operations, and to give ourselves an idea of all that she has brought into existence, in a word, which provides that sort of knowledge which truly constitutes the naturalist. Those who occupy their time with this point of view, which can include only a small number, take an equal interest in all the natural productions which they can observe.

The economic and pleasurable needs at first lead people to imagine in succession the different artistic parts used in the natural sciences. And when we reach a stage where we are thoroughly interested in learning about and understanding nature, these artistic parts still offer us help in this study. Thus, these same artistic parts are indispensably useful, whether to help us with the knowledge of particular things or to assist us in the study and the advancement of natural sciences, or finally to enable us to keep track of where we are in the midst of the enormous quantity of different things which are the basis of the main study.

Meanwhile, the philosophical interest which the sciences in question present, although less universally felt than the interest which stems from our economic needs, forces us to separate everything which belongs to art from what is the exclusive property of nature herself and to place within convenient limits the considerations which one must pay to the former concerns in order to attach to the latter all the importance which they deserve.

In the natural sciences, the artistic parts are the following:

1. the systematic distributions, whether general or particular; 2. the classes;3. the orders;4. the families;5. the genera;6. the nomenclature, whether of the various sections or of particular things.

These six sorts of groups generally used in the natural sciences are uniquely the products of the art we must use to arrange and divide and to prepare ourselves to study, compare, recognize, and refer to the different natural things we see. Nature has never made anything like this, and instead of doing ourselves an injustice and confusing our works with hers, we must recognize that in this business the classes, orders, families, genera, and nomenclatures are inventions of ours, which we are not capable of doing without but which we must use with care, subjecting them to acceptable principles, so as to avoid arbitrary changes which destroy all the advantages of such a system.

Undoubtedly, it is indispensable to classify the productions of nature and to establish among them different types of division, such as classes, orders, families, and genera. Finally we must determine what we call the species and assign special names to these various sorts of things. Our limited faculties demand that we do this; we must have some means like this to help us fix our knowledge about this

prodigious multitude of natural bodies which we can observe and which are infinitely varied amongst themselves.

But these classifications, several of which have been so fortunately devised by naturalists, together with the divisions and sub-divisions which they display, are entirely artificial tools. None of that, I repeat, is found in nature, in spite of the foundation which some parts of the natural scale known to us (apparently isolated examples) seem to give them. Moreover, we can state that among her productions nature has not really created fixed classes, orders, families, genera, or species, but only individuals which succeed each other and which look like those which produced them. Now, these individuals belong to infinitely diversified races, which are blend into each other in all forms and in all degrees of organic structure. Each of these individuals preserves itself without change, so long as there is no reason for change working on it.

Let us explore some specific developments concerning each of the six artistic parts used in the natural sciences.

Systematic Distributions. I call systematic distributions, whether general or particular, all series of animals or plants which do not conform to the order of nature, that is to say, which do not represent either the entire order or some part of that order, and consequently which are not founded on a consideration of well established interrelationships.

We are now perfectly justified in acknowledging that an order established by nature exists in her productions in each kingdom of living things: this order is the one according to which each of these bodies was originally formed.

This same order is unique, essentially without division in each organic kingdom, and can be known to us with the aid of an understanding of the particular and general interrelationships which hold among the different things which are the parts of these kingdoms. Living things which come at the two extremities of this order have, in essence, the least interrelationship and display in their organic structure and their form the greatest possible differences.

This very order is the one which must replace, to the extent that we understand it, these systematic or artificial distributions which we have been forced to create in order to organize in a convenient way the different natural bodies which we have observed.

In fact, with these various organic bodies, recognized by observation, at first we thought only of the usefulness and the ease of distinctions among them, and, so far as their distribution is concerned, we have taken so long to study the order of nature herself, that we did not even suspect its existence.

Hence have arisen all sorts of classifications, artificial systems and methods, based upon such arbitrary considerations, that these distributions change their principles and their natures almost as frequently as authors preoccupy themselves with the subject.

With the plants, the sexual system of Linnaeus, as ingenious as it is, offers a general systematic distribution; and so far as the insects are concerned, the entomology of Fabricius offers a particular systematic distribution.

It was necessary in recent years for the philosophy of natural sciences to make all the progress which we know it

has achieved, for us to be finally convinced, at least in France, of the need to study the natural method, that is to say, to seek out in our distributions the very order unique to nature, for this order is the only one which is stable, independent of all arbitrariness, and worthy of the natural scientist's attention.

Among the plants, the natural method is extremely difficult to establish, because of the obscurity which governs the characteristics of the inner organic structure of these living organisms and because of the differences which plants of various families can present. However, since the scholarly observations of Antoine Laurent de Jussieu, we have taken a giant step in botany in the direction of the natural method; numerous families have been formed by taking the interrelationships into account. But a firm determination of the general arrangement of all the families among themselves, and thus the general arrangement of the entire order, remains to be done. In truth, we have found the start of this order, but the middle and especially the end of it are still quite arbitrary.

The situation is not the same so far as animals are concerned. Their organic structure, much more pronounced, presents different systems which are easier to grasp. This has allowed work on them to move further ahead. In addition, the very order of nature, in the animal kingdom, is now sketched out in its principal groups in a stable and satisfactory way. Only the limits of the classes, their orders, families, and genera are still dealt with arbitrarily.

If systematic distributions among the animals are still made, these distributions, at least, are only particular, like

those for things which belong to one class. Thus, up to the present, the distributions which we have made of the fish and the birds are still systematic distributions.

In dealing with living things, the more one goes down from the general to the particular, the less essential are the characteristics which serve for the determination of interrelationships, and thus the more difficult it is to come across the very order of nature.

Classes. The name class is given to the first type of general divisions established in a kingdom. The other divisions made among these classes then receive other names. We will mention that in a moment.

The more advanced our understanding of the interrelationships among the things making up a kingdom becomes, the more the classes established for the initial division of this kingdom are good and appear natural, if, in forming them, one had classes which destroyed the hierarchy and the simplicity of the divisions which Linnaeus proposed in his example and which have been generally adopted.

The diversity of things which belong to a class, whether of animals or plants, is sometimes so large that it is then necessary to establish many divisions and sub-divisions among the objects of this class. But the interest of science wants the artistic part to be always as simple as possible, in order to facilitate study. Now, this interest allows, undoubtedly, all the necessary divisions and sub-divisions, but it is opposed to all the divisions and subdivisions having special designations. It is necessary to set a limit to the abuses of nomenclature. Without such a limit, nomenclature would

become a more difficult subject to understand than the very things which one ought to be considering.

Orders. The name order is given to the main divisions of the sort which initially divide a class. If these divisions promote a method for creating others by subdividing them, these subdivisions are no longer orders. It would be very inconvenient to give them that name.

For example, the class of mollusks makes it easy to establish among these animals two large main divisions, the ones having a head, eyes, and so on and reproducing by coupling, while the others are headless, eyeless, and so on, and do not undergo coupling in reproduction. The cephalid mollusks and the acephalid mollusks must therefore be considered the two orders of this class. However, each these orders can be divided into several distinguishable sections. Now, this consideration is not a reason which can justify giving the name order, nor even that of sub-order, to each of the sections concerned. Thus, these sections dividing the orders can be considered as sections, just as some large families are themselves susceptible to being further sub-divided.

Let us preserve in the artistic part the great simplicity and the fine hierarchy established by Linnaeus, and if we frequently need to sub-divide the orders (i.e., the main divisions of a class), let us make these sub-division as many as necessary without giving them special designations.

The orders which divide a class must be determined by important characteristics which extend to all the things constituting each order, but we must not assign to them a special name applicable to the objects themselves.

The same thing must take place with regard to the sections which necessity requires one to make in the orders of a single class.

Families. We give the name family to the parts of the natural order recognized in one or another of the kingdoms of living things. These parts of the natural order are, on the one hand, not as large as the classes and even of the orders and, on the other hand, they are larger than the genera. But however natural families may be, all the genera which they include being conveniently grouped by their true similarities, the limits which one places around these families are always artificial. Thus, to the extent that we will study further the productions of nature and observe new ones, we will see, among naturalists, constant variations in the limits of families. Some naturalists divide a family into several new families, others combine several families into a single one, and still others make even more additions to an already known family, enlarging it, thus pushing back the limits which had been assigned to it.

If all the races (what are called the species) which belong to a kingdom of living creatures were perfectly known and if the true interconnections which occur between each of these races and between the different groups which they form were similarly understood, in a way in which everywhere the interconnection of these races and the placing of their various groups followed the natural interconnections of these things, then the classes, orders, sections, and genera would be families of different sizes; for all these sections would be large or small parts of the natural order.

In the case I have just mentioned, there is no doubt that nothing would be more difficult than to assign limits to separate these different sections. Arbitrary designations would make them vary constantly, and we would agree about only those which some gaps in the series clearly established for us.

Fortunately, in order to carry out the art which we need to introduce into our distributions, there are so many animal and plant races still unknown to us and there are so many which will probably stay that way for ever, because the places where they live and other circumstances will always obstruct, that the resulting gaps in the extent of the series, whether of animals or plans, will for a long time yet, and perhaps forever, provide us ways of limiting most of the groups which must be formed.

Usage and a sort of necessity demand that we assign to each family as to each genre a particular name applicable to the objects which compose it. Hence, it follows that the variations in the limits of families, their extent, and their determination will always be a reason for changes in their nomenclature.

The Genera. We give the name genus to the groups of races, called species, brought together following a consideration of their interconnections and constituting thus small limited series by the characteristics with which one chooses arbitrarily to define them.

When a genus is created well, all the races or species which it includes are similar in their most essential and most numerous characteristics, and they must be ranked naturally one beside the other, without differences amongst them

except by less important characteristics sufficient to distinguish them.

Thus, well constructed genera are really small families, i.e., true parts of the very order of nature.

But just as the series to which we give the name families are susceptible to variation in their limits and their extent, through the opinion of authors who arbitrarily change the criteria which they use to form them, so the limits which define the genera are also similarly exposed to infinite variation, because different authors, according to their whim, change the characteristics used to determine them. Now, since the genera demand that a particular name be assigned to each of them and since each variation in the determination of a genre brings with it almost always a change in the name, it is difficult to express how much the constant changes in the genera harm the advancement of the natural sciences, by creating cumbersome synonyms, overloading the nomenclature, and making the study of these sciences difficult and disagreeable.

When will naturalists consent to subject themselves to the principles of a common agreement in order to regulate themselves in a uniform way in the establishment of genera, and so on? But seduced by the consideration of the natural interconnections which they recognize between the objects which they have compared, almost all of them still think that the genera, families, orders and classes which they establish are really in nature. They do not attend to the fact that the good series which they manage to form with the aid of studying interrelationships are really in nature, for they are the large or small portions of nature's order but that the lines

of separation which they are concerned to draw from one part to another to divide up the natural order are not at all natural.

Thus, the genera, families, various sections, orders, and even the classes are really parts of art, however natural the well formed series which make up the different groups may be. Without doubt, their establishment is necessary, and their aim has an evident and indispensable utility. However, so as not to destroy, by the abuses which always recur, all the advantages which these artistic endeavours provide us, it is necessary that the creation of any one of them must be subject to principles, rules agreed to once and for all. Then all naturalists need to follow them.

Nomenclature: Here we are concerned with the sixth of the artistic practices which we must use for the advancement of the natural sciences. We call nomenclature the system of names which we assign, whether to particular things, like each race or species of living things, or to different groups of these things, like each genus, family, and class.

In order to designate clearly the object of our nomenclature, which includes only the names given to species, genera, families and classes, we must distinguish nomenclature from the other artistic practice which we call technology, the latter being uniquely relevant to the denominations we assign to the parts of natural bodies.

"All the discoveries, all the observations of naturalists would necessarily fall into oblivion and be lost for society's use, if the things which they observed and sorted out had not received a name which could serve

to designate them immediately, when we talk about them or refer to them." (Dict. De Botanique, art. Nomenclature)

It is quite evident that nomenclature in natural history is an artistic practice and that it is a means which we have had to use to fix our ideas concerning the natural productions we observe and to communicate either these ideas or our observations concerning the objects with which these ideas deal.

Without doubt this artistic practice must be subjected, like the others, to agreed-upon and universally followed rules. But I must note that the abuses which it manifests everywhere in the uses to which it has been put and of which we have so many reasons to complain, arise mainly from those which were introduced and which still daily multiply in the other artistic practices already referred to.

In fact, because the lack of agreed upon rules concerning the formation of genera, families and even classes exposes these artistic practices to all sorts of arbitrary variations, the nomenclature has gone through a series of changes without limits. It can never be fixed as long as this lack remains, and the number of synonyms, already immense, will always increase and will become more and more incapable of fixing such a disorder, which cancels all scientific advantages.

If we had considered that all the lines of separation which we can trace in the series of objects which make up one of the kingdoms of living things are really artificial, except those which result from gaps needing to be filled, none of this would have happened. But this point has not

been considered; people have not entertained doubts about the matter, and almost every day right up to the present, naturalists have had nothing else in view but to establish distinctions among things. Let me demonstrate this point.

"In fact, to reach a point where we could gain and keep using all these natural things within our reach and which we can make serve our needs, we felt that an exact and precise determination of the characteristics unique to each thing was necessary and thus that we had to seek out and determine the particularities of organization, structure, form, proportion, and so on, and so on, which differentiate the various natural bodies, in order to be able always to recognize them and distinguish them from each other. This is what naturalists, through examining objets, have succeeded in achieving, up to a certain point.

"This part of the work of naturalists is the one which is the most advanced. For good reason, in approximately the past century and a half, we have made immense efforts to improve the work because it helped us to understand what was newly observed and to remember what we had already learned and because it had to fix our knowledge of things whose properties are or will be then be recognized as useful to us.

"But the naturalists leaned too heavily on the use of all these ideas about the lines of separation which they were able to get to divide up the general series,

whether of animals or plants. They turned their attention almost exclusively to this sort of work, without considering it from a realistic point of view and without thinking of listening to each other, that is, without establishing first convenient rules to limit the range of each part of this large enterprise and to establish the principles for each method of determining things. Thus, a number of abuses were introduced, so that each one changed arbitrarily the criteria for the formation of classes, orders, and genera, and continually published different systems of classification. Hence, the genera underwent constant changes without limits, and the productions of nature, as a consequence of this poorly thought out process, continually change their names.

As a result, nowadays the number of synonyms in natural history has become frightening, each day the science becomes more and more obscure, and it wraps itself up in almost insurmountable difficulties. The best human efforts to establish ways to recognize and distinguish all that nature presents to observation and use are transformed into an immense maze which one trembles to enter, with good reason." Discours d'ouvert. Du Cours de 1806, p. 5 and 6.

There we see the consequences of our forgetting to distinguish what really belongs to art and what is unique to nature and of forgetting to concern ourselves with finding agreed-upon rules to determine less arbitrarily the divisions which need to be made.

Chapter TwoThe Importance of Considering Affinities

Among living bodies, the term affinity (between two things being examined comparatively) has been given to analogous or similar traits, taken from the totality or the general features of their parts, but with more value attached to the most essential parts. The more extensive and similar these traits, the more significant the affinities between the objects which display them. They indicate some sort of family connection among the living things under consideration and make one aware of the need to bring them together in our distributions in a manner proportional to the significance of their affinities.

What a change the natural sciences have undergone in their progressive march since people started to pay serious attention to a consideration of these affinities, and above all since we determined the true principles concerning these affinities and their value!

Before this change, our botanical distributions were entirely ruled by the arbitrary and competitive artificial systems of all authors; and in the animal kingdom, the invertebrates, which include the largest part of known animals, showed in their distribution the most disparate collections, some under the name insects and others under the name worms, including animals which, from any consideration of their affinities, are the most different and the most widely separated from each other.

Fortunately, matters have now changed in this respect. And from now on, if we continue to study natural history, its progress is guaranteed.

Consideration of the natural affinities prevents all arbitrariness on our part in the attempts we make to arrange organic things methodically. It demonstrates the natural law which must guide us in the natural method. It forces the views of naturalists to agree about the rank which they assign at first to the principal groups which make up their arrangements, and later about the particular objects which make up these groups. Finally, such a consideration constrains them to reproduce the very order which nature has followed in giving life to her productions.

Thus, everything concerning the affinities existing among the different animals must constitute, before any division or classification of them, the most important object of our research.

In this discussion here of a consideration of the affinities, it is not a matter only of those which exist between the species; it is at the same time a question of determining the general affinities of all the orders close to or far away from the groups which one must compare.

Although the interrelationships are very different in value depending on the importance of the parts which establish them, they can nevertheless extend to include the shape of the external parts. If they are so significant that, not only the essential parts but even the exterior parts present no discernible difference, then the objects under scrutiny must be individuals of the same species. But if, in spite of the extent of their affinities, the exterior parts display perceptible

differences which, however, are always less significant than the essential similarities, then the objects under scrutiny must be considered different species of the same genus.

The important study of affinities is not limited to comparing classes, families, and even species amongst themselves in order to determine the interrelationships which exist among these objects. It includes also a consideration of the parts which make up the individuals. In comparing among them the same sorts of parts, this study discovers a reliable means to recognize either the identity of individuals of a common race or the difference between distinct races.

In fact, it has been noted that the proportions and the arrangements of the parts of all the individuals making up a species or a race always appear the same and thus appear to remain constant. Hence. it has reasonably been concluded that, after an examination of a few isolated parts of an individual, it is possible to determine to what species, familiar or new to us, these parts belong.

This method is very conducive to the advancement of our knowledge about natural productions at the time which we are observing. But what we determine from this method can be valid only for a limited time period. For with respect to the condition of their parts, the races themselves change to the extent that the circumstances influencing them undergo significant transformation. True, since these transformations occur only extremely slowly, at a rate which makes them always imperceptible to us, the proportions and arrangements of the parts always appear the same to the observer, who in practice never sees them change. And when he comes across some which have undergone these changes, since he has not

been able to observe them, he assumes that the perceptible differences have always existed.

It is nevertheless true than in comparing the same type of parts belonging to different individuals, it is easy to determine reliably the close or distant affinities which exist between these parts and, consequently, to recognize if these parts belong to individuals of the same or of different races.

It is only the general conclusion which is faulty, having been drawn too rashly. I will have more occasion to establish this point in the course of this work.

The affinities are always incomplete when they deal only with a solitary analysis, that is to say, when they are determined only after an analysis of one part taken by itself. But however incomplete, these affinities based on the inspection of a single part have nevertheless an importance directly proportional to the essential nature of the part under scrutiny, and vice versa.

Thus, there are determinable degrees among the known affinities and important values among the parts capable of establishing these interrelationships. To be sure, this knowledge would have remained without practical use if, in living creatures, we had not distinguished the most important parts from those of less importance, and if, among these important parts, which are of several types, we had not found the principle appropriate to establishing among them non-arbitrary values.

The most important parts which must establish the principal affinities in the animals are those essential to the preservation of their life and in the plants those essential to their reproduction.

Thus, in the animals, we will always determine the main interrelationships according to the interior organic structures. In the plants we will always seek out in the parts which produce the fruit the affinities which can hold between different living things.

But since, with animals and plants, the most important parts for analysis in the search for affinities are of different types, the only principle which it is convenient to use to determine in a non-arbitrary manner the degree of importance of each of these parts consists in considering either the most important use which nature makes of it or the special importance of the faculty resulting from that part in animals which possess it.

In the animals, where the internal organic structure provides the major affinities for analysis, three sorts of special organs are, with good reason, selected out from the others as the most relevant for establishing the most important interrelationships. The following list indicates them in order of their importance.

1. The organ of feeling. The nerves, since they have a central connection, whether unique (as in the animals with a brain) or multiple (as in those which have a longitudinal marrow with ganglia)

2. The organ of respiration. The lungs, gills and the tracheae;

3. The organ of circulation. The arteries and the veins, most commonly with an active central point, the heart.

The first two of these organs are more frequently employed in nature, and thus are more important than the third, that is, the organ of circulation. For the latter disappears after the crustaceans; whereas, the first two still extend to the animals in the two classes which follow the crustaceans.

Finally, of the first two, the organ of feeling must have more value for establishing affinities, for it produces the most eminent of the animal faculties. Moreover, without this organ muscular action would not take place.

If I was going to talk about plants, in which the parts essential for reproduction are the only ones which provide the main characteristics for determining their affinities, I would present these parts in their order of value or importance as follows:

1. The embryo, its accessories (the cotyledons, the perisperm), and the seed which contains it;

2. The sexual parts of flowers, such as the pistil and the stamens;

3. What surrounds the sexual parts; the corolla, the calyx, and so on;

4. The seed casing, or the pericarp;

5. The reproductive bodies which do not need any pollination.

These principles, for the most part recognized, give a consistency and a reliability to the natural sciences which they did not have previously. The affinities which have been

determined by conforming to such principles are not at all subject to variations of opinion. Our general distributions are becoming secure, and to the extent which we perfect them with the help of these methods, they will get closer and closer to the very order of nature.

After having sensed the importance of the analysis of affinities, in fact, we saw the birth of those attempts made (above all in the last few years) to establish what is being called the natural method, something which is only the sketch traced by man of the route nature follows to brings its productions into existence.

Nowadays in France it is no longer a question of those artificial systems based upon characteristics which jeopardize the natural affinities between the objects subjected to such systems, ones which establish division and distributions detrimental to the advancement of our knowledge about nature.

So far as animals are concerned, we are now convinced, for good reasons, that we can determine the natural affinities only through their organic structures. Consequently, zoology will derive all the insights necessary for the determination of these affinities from comparative anatomy. But it is important to note that it is the particular facts which we must assemble from the works of the anatomists who have set out to discover them, and not always the conclusions which they have drawn from these facts. For too often, these conclusions encourage opinions which could lead us astray and prevent us from grasping nature's laws and her true design. It appears that each time someone observes any new fact whatsoever, he is condemned to hurl himself

into error through his desire to assign a cause to it; his imagination is so fecund in the production of ideas, because he neglects too much the need to guide his judgments by the totality of the collection which observations and the other assembled facts can present to him.

When we work on natural affinities between objects and judge these interrelationships well, bringing together the species according to this analytical principle and assembling them in groups within certain limits, the groups make up what are called genera. Similarly the genera, organized according to an analysis of the affinities and combined also into groups larger than theirs, form what are called families. When these families are combined in the same way under the same analytical principle, they form the orders. The latter by the same process first separate out the classes. Finally, these groups divide up each kingdom into its principal sections.

Therefore, the well-determined natural affinities must guide us in forming our collections, when we establish the divisions of each kingdom into classes, each class into orders, and each order into sections or families, each family into genera, and each genus into different species, as required.

We are perfectly justified in thinking that the total series of beings making up part of a kingdom, once that series is distributed in an order subject throughout to the analytical principle of affinities, represents the very order of nature. However, as I showed in the preceding chapter, it is important to bear in mind that the different types of divisions which we must establish in this series so that we can know the objects in it more readily are not part of nature at all and

are truly artificial, although they display portions of the same order which nature has set up.

If we add to these considerations the points that in the animal kingdom the affinities must be determined mainly according to organic structures and that the principles which we must use to establish these affinities must not leave the least doubt about what they are based on, we will have, in all these matters, solid foundations for zoological philosophy.

We know that all science must have its philosophy and that by this route science makes real progress. It is futile for naturalists to waste their time in describing new species, seizing upon all the slight modifications and the small particularities of their variations to augment the immense list of species drawn up in a list, in a word, setting up genera in various ways and constantly changing the analytical principles used to characterize them. If science neglects philosophy, its progress will not be real, and the entire work will remain imperfect.

It is really only since we set about establishing the close or distant interrelationships existing among the various natural productions and among the objects comprising the different groups we have created among these productions that the natural sciences have acquired some reliability in their principles and a philosophy which turns them into real sciences.

How much our arrangements and our classifications would improve each day from the sustained study of the affinities among objects.

In fact, by studying these affinities I recognized that the infusorian animals could no longer be grouped with the

polyps in the same class, that the radiates must no longer be confused with the polyps, and that the soft ones, like the medusas and other neighbouring genera which Linnaeus and even Bruguière placed among the mollusks, are essentially like the echinoderms and should form a special class with them.

Again, by studying affinities I became convinced that the worms form an isolated group, including animals very different from those which make up the radiates and (for stronger reasons) the polyps, that the arachnids could no longer be a part of the class of insects, and that the cirrhipedes were neither annelids nor mollusks.

Finally, by studying affinities I managed to make a number of essential improvements to the arrangement of mollusks, and I recognized that the pteropods, although distinct, because of their affinities are very nearly related to the gasteropods and must be placed between the acephalic mollusks, to whom they are close, and the gasteropods. These pteropods have no eyes, like all the acephalids, and almost always lack a head; even the Hyalae have only the appearance of one. See the specific distribution of Mollusks in Chapter Seven, which ends this first part.

As for plants, when the study of the affinities among the different recognized families has given us more insight and we better understand the rank which each of them must occupy in the general series, then the distribution of these living bodies will leave nothing to be determined arbitrarily and will conform more to the very order of nature.

This, the importance of the study of affinities among the objects we observe is so evident that we must nowadays

look upon this study as the most important of those which can advance the natural sciences.

Chapter ThreeConcerning Speciation Among Living Things and the Idea

Which We Should Attach to This Word

It is not a futile pursuit firmly to establish the idea which we should form about what are called species among living creatures and to investigate whether it is true that species have an absolute constancy, are as old as nature, and have all existed originally just as we see them today, or whether, subject to changes which could have taken place in the circumstances relevant to them, they have not changed their characteristics and shape with the passage of time (although extremely slowly).

The illumination of this question is not only of interest to our zoological and botanical knowledge but also is essential to the history of the earth.

I will show in one of the chapters which follow that each species has received from the influence of the circumstances which it encounters over a long period the habits which we know about and that these habits have themselves exerted influences on the parts of each individual of the species, to the point where they have modified these parts and have made them appropriate to the acquired habits. Let us first examine the idea which has developed about what is called a species.

We call species every collection of similar individuals produced by other individuals just like themselves.

This definition is exact, for every individual enjoying life always resembles very closely the one or those from which it came. But we add to this definition the assumption that the individuals who make up a species never vary in their specific characteristics and that therefore the species has an absolute constancy in nature.

It is precisely this assumption that I propose to contest, because clear proofs obtained through observation establish that it is not well founded.

The assumption almost universally admitted that living things make up eternally distinct species on account of their invariable characteristics and that the existence of these species is as ancient as nature herself was established at a time when people had not observed nature sufficiently and when the natural sciences were still almost nothing. The assumption is contradicted every day in the eyes of those who have looked at a great deal and have followed nature for a long time, and who have reaped the benefits of the large and rich collections in our museum.

Moreover, all those who are very busy studying natural history know that nowadays naturalists are extremely embarrassed in their attempts to define the objects which they have to consider species. In fact, not knowing that species have a constancy only relative to the duration of the circumstances in which all the individuals composing them are found and that some of these individuals, having undergone variations, make up races which modulate into some other neighbouring species, naturalists make decisions arbitrarily, by describing some individuals observed in different countries and in various environments as varieties

and others as species. As a result, that section of work concerning the determination of species is becoming day by day increasingly defective, that is, more embarrassing and confusing.

In truth, it has been observed for a long time that there exist collections of individuals who so resemble each other in their organic structure, as well as by the totality of their parts, and who remain in the same condition generation after generation for as long as we have known about them that people have believed themselves justified in regarding these collections of similar individuals as making up just as many invariable species.

Now, not having attended to the fact that the individuals of a species must perpetuate themselves without variation, as long as the circumstances which influence their manner of life do not essentially vary and the existing prejudices agreeing well enough with the successive regeneration of similar individuals, people have assumed that each species did not vary, was also as old as nature, and was uniquely created by the work of the Supreme Author of everything which exists.

There is no doubt that nothing exists except by the will of the sublime Author of everything. But can we assign some rules to Him in the execution of His will and establish the method which He followed in this matter? Could not His infinite power have been capable of creating an order of things which gave life successively to everything which we see, as well as to everything existing which we do not know about?

To be sure, whatever His will, the immensity of his power is still the same and whatever the manner in which the Supreme Will carried out His work, nothing can diminish His grandeur.

Therefore, respecting the decrees of this infinite wisdom, I confine myself within the limits of a simple observer of nature. Then, if I manage to unravel something of the progress which nature has followed to bring about its productions, I will say, without fear of being wrong, that it has pleased her Author that nature has had this faculty and this power.

The notion of species among living creatures which people formed was very simple, easy to grasp, and seemed confirmed by the constancy in the apparent form of individuals which reproduction or generation perpetuated. Such individuals create for us a great number of those alleged species which we see every day.

However, the more we advance our knowledge of the different organic bodies which cover the surface of the earth almost everywhere, the greater becomes our embarrassment about determining what ought to be regarded as a species and, for even more compelling reasons, about limiting and distinguishing genera.

The more we collect the productions of nature and our collections grow richer, the more we see almost all the gaps being filled and our lines of separation being erased. We find ourselves reduced to an arbitrary determination, which sometimes leads us to seize upon the least differences among the varieties to form the characteristic of what we call species. Sometimes this makes us call certain individuals with

slight differences a variety of some species. Other people consider these individuals constitute a separate species.

Let me repeat myself: the more our collections increase, the more we encounter proofs that everything is more or less nuanced, the remarkable differences disappear, and as often as not nature makes available to us for the creation of distinctions only minute and, so to speak, puerile particularities.

How many genera, among animals and plants, are so extensive in the quantity of species which people assign to them, that the study and the definition of these species are now almost unworkable! The species in these genera, arranged in a series and set beside each other according to an analysis of their natural affinities, display, along with those which are close to them, differences so slight that they are modifications of each other and these species get confused, in some way, amongst each other, leaving almost no way of determining in some explicit way the small differences which distinguish them.

Those who have concerned themselves long and diligently with the determination of species and who have looked at rich collections are the only ones who can know at what point, among living things, species merge into each other and who could convince themselves that, in those places where we see isolated species, the phenomenon occurs only because we are missing other closely related species which we have not yet collected.

For all the above remarks, I do not wish to state that existing animals form a very simple series, equally modified throughout. But I do say that they form a branching series,

with irregular gradations, something which has no discontinuity in its parts or which, at least, has not always had them, if it is true that as a result of some lost species such discontinuity occurs here and there. From this it follows that species which end each branch of this general series have, at least on one side, other closely related species which meld into them. This well known state of things leads me now to provide an illustration.

I do not require any hypothesis nor any assumption for such a demonstration. I call all observing naturalists to vouch for its truth.

Not only many genera but some entire orders and sometimes even the classes already offer us almost complete sections of the state of things which I am going to point to.

Now, when, in this example, one arranges the species in a series, placing them correctly following their natural affinities, if you choose one and then, making a jump over several others, take another species a little distant, these two species, when compared, will present to you major differences between them. This was the manner in which we started to see nature's productions which we find most frequently within reach. Then the generic and specific distinctions were very easy to establish. But now that our collections are extremely profuse, if you follow the series which I have cited immediately above from the species you first chose right up to the one which you selected second (which is very different from the first), you will reach that second species through a series of slight modifications without having noticed distinctions worthy of attention.

Here is the question: What experimental zoologist or botanist has not explored the basis of what I have just revealed?

How then are we to study species or how are we able to determine them with a reliable method, among this multitude of polyps of all the orders, radiates, worms, and, above all, insects, where the individual order butterfly, Phalaena, Noctua, Tinea, flies, Ichneumon, Curculio, Cerambix, chafers, rose-chafers, and so on and so on already display so many closely related species, modifying into and almost overlapping each other?

What a crowd of shell creatures the mollusks show us from all countries and all seas, eluding our ways of distinguishing them and wearing out our resources on this question.

Go back up to the fish, reptiles, birds, even to mammals. You will see everywhere, apart from the gaps which still have to be filled, the modifications which link up neighbouring species, even genera, leaving hardly any places for our ingenuity to establish good distinctions.

And in its various parts does not botany, which focuses on the other series making up the plants, display exactly the same state of things?

In fact, what difficulties are not experienced nowadays in studying and determining species in the genera Lichen, Fucus, Carex, Poa, Piper, Euphorbia, Erica, Hieracium, Solanum, Geranium, Mimosa, and on and on?

When we formed these genera, we knew only a small number of their species; thus, they were easy to distinguish.

But now that almost all the gaps between them have been filled, our specific differences are necessarily minute and very frequently insufficient.

Having well established this state of affairs, let us examine the causes which can have given rise to it. Let us see if nature possess means for that and if observation could have given us insight into this question.

A number of facts teach us that, to the extent that the individuals of one of our species change their situation, climate, manner of life, or habits, they obtain from that change influences which little by little alter the constancy and the proportions of their parts, shape, faculties, even their organic structure, with the result that everything in them participates, over time, in the mutations which they have experienced.

In the same climate, significantly different situations and exposures at first simply induce changes in the individuals who find themselves confronted with them. But as time passes, the continual difference in the situation of the individuals I'm talking about, who live and reproduce successively in the same circumstances, leads to changes in them which become, in some way, essential to their being, so that after many generations, following one after the other, these individuals, belonging originally to another species, find themselves at last transformed into a new species, distinct from the other.

For example, if the seeds of a grass or of any other plant common to a humid prairie are transported, by some circumstance or other, at first to the slope of a neighbouring hill, where the soil, although at a higher altitude, is still

sufficiently damp to allow the plant to continue living, if then, after living there and reproducing many times in that spot, the plant little by little reaches the almost arid soil of the mountain slope and succeeds in subsisting there and perpetuates itself through a sequence of generations, it will then be so changed that botanists who come across it there will create a special species for it.

The same thing happens to animals which circumstances have forced to change their climate, manner of life, and habits. But for these, the causal influences which I have just mentioned require even more time than is the case with plants in order to effect notable changes in the individuals.

The idea of including, in the name species, a collection of similar individuals who perpetuate creatures like themselves through reproduction and who have thus existed in the same form for as long as nature necessarily requires that the individuals of the same species, in their reproductive acts, cannot mate with the individuals of another species.

Unfortunately, observation has demonstrated and still establishes every day that this idea has no foundation whatsoever. For hybrids, very well known among plants, and the matings which we often see between individuals of very different species among animals attest to the fact that the limits between these species, supposedly constant, were not as firm as people have imagined.

To be sure, often nothing results from these odd matings, above all when they involve very different types, and then the individuals produced are, in general, infertile. But then again, when the disparity is less great, we know that

the flaws in question do not occur. Now, this method by itself is sufficient to create varieties gradually which then become races, and which, in time, make up what we call species.

In order to evaluate whether the traditional idea of species has some real foundation, let us look again at points which I have already established. They enable us to see the following:

(1) All organic bodies of our earth are true products of nature, which she has brought forth successively over a long period of time; (2) In her progress, nature began, and begins again every day, by creating the simplest organic bodies, and she does not directly create anything except by this process, that is to say, by these first beginnings of organic structure which are designated by the expression spontaneous generation. (3) The first beginnings of animals and plants were formed in appropriate places and circumstances. Once the faculties of a commencing life and of organic movement were established, these animals and plants of necessity gradually developed organs, and, in time, they diversified these organs, as well as their parts. (4) The faculty of growth in each portion of an organic body is inherent in the first effects of life; it gave rise to different ways of multiplication and reproduction of individuals. In this process, the progress acquired in the composition of the organic structure and in the shape and diversity of parts was maintained.

(5) With the help of a sufficient lapse of time, of circumstances which were necessarily favourable, of changes which every point on the surface of the earth has successively undergone, in a word, with the assistance of the power which new situations and habits have for modifying the organs of a body endowed with life, all those which exist now have been imperceptibly shaped just as we see them. (6) Finally, after a sequence of events like the above, living bodies have each experienced greater or lesser changes in the condition of their organic structure and their parts. What we call species have been created in this way imperceptibly and successively among them; they have a constancy which is only relative to their condition and cannot be as old as nature. But, someone will say, when people want to assume

that with the help of a great deal of time and an infinite variation in circumstances, nature has gradually formed the various animals which we know about, would they not have this assumption challenged by the single consideration of the admirable diversity which we see in the instincts of these different animals and by the consideration of the marvels in every genus which their various sorts of work offer?

Dare one carry the systematic spirit so far as to say that it is nature alone which has created this astonishing diversity of means, tricks, dexterity, precaution, and patience, so often illustrated to us by the industry of animals? Is not what we observe in this respect in the class of insects alone a thousand times more than sufficient to make us feel that limiting the power of nature would not permit her to produce on her own

so many marvels and to impress on us the most persistent belief that here the will of the supreme Author of everything was necessary and alone sufficed to bring into existence so many admirable things?

Without doubt, one would have to be foolhardy or rather entirely idiotic to claim to assign limits to the power of the first Author of everything. But, by that alone, no one can dare to say that this infinite power could not have willed what nature herself shows us it has willed.

This being the case, if I discover that nature herself brings about all these wonders which have just been mentioned, that she has created organic structures, life, even feeling, that she has multiplied and diversified within limits which we do not know, the organs and faculties of organic bodies in whom she supports and propagates existence, that she has created in animals, by the sole route of needs, which establish and direct habits, the source of all actions, all faculties, from the simplest right up to those which make up instinct, work, and finally reasoning, must I not recognize in this power of nature, that is to say, in the order of existing things, the work of the will of her divine Author, who has been able to will that she has this ability?

Will I admire less the grandeur of the power of this first cause of everything if it has pleased Him that things were like this, that if, by so many acts of His will, this power was occupied and still is continually occupied with the details of all the particular things of creation, all the variations, all the developments and improvements, all the destruction and all the renewals, in a word, of all the transformations which universally happen in existing things?

Now, I hope to prove that nature possesses the means and the abilities necessary for her to produce by herself what we admire in her.

However, another objection is that everything which we see announces, concerning the condition of living things, an unalterable constancy in the conservation of form. And it is believed that all the animals whose history has been handed down to us in the past two or three thousand years have always been the same and have lost nothing and acquired nothing in the improvement of their organs and in the shape of their parts.

Moreover, in order to give this apparent stability over a long period the status of a verified fact, an attempt has just been made to provide particular written proofs for it in the Report On the Collections of Natural History Brought Back from Egypt by M. Geoffroy. Those writing the report express themselves on this point in the following way:

"First, the collection has this remarkable quality, that we can say it contains animals of all centuries. For a long time now, people have wanted to know if species change their form with the passage of time. This apparently futile question is essential to the earth's history and, consequently, to the solution of a thousand other questions, which are not irrelevant to the most serious purposes of human reverence.

We have never been in a better position to make a decision about a large number of remarkable species and for several thousands of others. It appears that the superstition of the ancient Egyptians was inspired by

nature, with a view to leaving a monument of her history. . . .

"It is not possible, the writers of the report continue, to control one's imaginative excitement when one sees still preserved with the smallest bones, the smallest hairs, and perfectly recognizable, such an animal which had, two or three thousand years ago, priests or altars in Thebes or Memphis. But without losing ourselves in all the ideas which this link generates, let us limit ourselves to revealing to you that, as a result of this part of Geoffroy's collection, these animals are perfectly similar to today's." Annales du Muséum d'Hist. natur., vol. I, p. 235, and 236.

I do not deny the conformity in the appearance of these animals with individuals of the same species alive today. Thus, the birds which the Egyptians adored and embalmed, two or three thousand years ago, are still totally similar to those which live at present in that country.

It would surely be really odd if the case was otherwise. For the situation of Egypt and its climate are still to a very large degree what they were at that period. Now, the birds which live there at present are still in the same circumstances where they were then and could not have been forced to change their habits.

Moreover, who does not sense that birds, which can so easily move on and choose places agreeable to them, are less subject to variation in local circumstances than many other animals and thus less challenged in their habits.

In fact, there is nothing in the observation mentioned above which contradicts the ideas I have revealed in this matter and, above all, which proves that the animals under discussion have existed for all time in nature. It proves only that they were present in Egypt two or three thousand years ago. And anyone in the habit of thinking about things, while at the same time observing what nature shows us of the monuments to its own antiquity, easily appreciates the value of a duration of two or three thousand years in comparison with that antiquity.

In addition, we can be sure that this apparent stability of things in nature will always be taken by common opinion as the truth of things, because, in general, people do not judge anything except in relation to themselves.

For the man who, in this matter, judges only according to changes which he perceives himself, the intervals between these mutations are conditions of stability which appear unlimited to him, because of the brevity of the lifetime of the individuals in his species. Moreover, since the records of his observations and the factual notes which he has been able to enter into his accounts go back only a few thousand years, a length of time infinitely great compared with him, but extremely small compared to durations which have witnessed the occurrence of the great changes the surface of the earth has undergone, everything appears stable on the planet which he inhabits, and he is encouraged to dismiss the signs presented to him everywhere by the monuments piled up around him or buried in the soil under his feet as he walks.

Quantities of space and time are relative. If man really wishes to imagine this truth, then he will be reserved in his

judgments about the stability which he attributes in nature to the state of things which he observes. See in my Recherches sur les corps vivans, l'appendice, p. 141.

In acknowledging the imperceptible changes in species and the modification which individuals undergo, to the extent that they are forced to vary their habits or to acquire new ones, we are not confined solely to a consideration of the very small extents of time which our observations can include to allow us to see these changes. For, in addition to this induction, a number of facts collected for many years now also illuminate the question which I am examining, in such a way that it does not remain uncertain. And I can say that nowadays our observational knowledge is too advanced for the answer we are looking for not to be obvious.

In addition the fact that we know about the influences and the results of heterogeneous reproduction, we certainly know nowadays that a forceful and sustained change in the environment and in the habits and ways of life of animals works to bring about, after a suitable length of time, a very remarkable change in the individuals exposed to it.

The animal which lives freely in the plains where it habitually runs quickly and the bird which meets its needs as it continually crosses huge expanses in the air, when caged up, one in the compartments of a menagerie or in our stables, the other in our cages or in our poultry yards, there undergo over time significant influences, especially after a sequence of reproductive cycles in a condition which makes them acquire new habits.

In that new location, the first loses a large part of its lightness and agility. Its body becomes more dense; its limbs

lose power and suppleness, and its faculties are no longer the same. The second becomes heavy, hardly knows how to fly any more, and acquires more flesh in all its parts.

In the sixth chapter of this first part, I will have occasion to prove by well known facts the power of changes in circumstances to give animals new needs and to lead to new actions, the power of repeated new actions to bring about new habits and new tendencies, and finally, the power of the more or less frequent use of this or that organ to modify that organ, whether by making it stronger, developing and enlarging it, or by making it more feeble, diminishing and weakening it, and even making it disappear.

In the case of plants, we will see the same thing concerning the effects of new circumstances on their manner of living and on the condition of their parts. The result is that we will no longer be astonished to see the considerable changes which we have made in those plants we have cultivated for a long time.

Thus, among living things, nature, as I have already said, offers us in an indisputable manner only individuals which succeed each other in sequence one after the other in reproduction and which come from each other. But species among them have only a relative constancy and are not invariable except temporarily.

Nevertheless, to facilitate our study and our knowledge of so many different bodies, it is useful to give the name species to the entire collection of similar individuals which reproduction perpetuates in the same condition, as long as their living circumstances do not change sufficiently to vary their habits, characteristics, and shape.

On Species Which Have Been Called Lost

There is still for me the issue of knowing if the means which nature adopted to assure the conservation of species or races has been so inadequate that entire races have now been wiped out or lost.

However, the fossil remains which we find buried in the soil in so many different places present us with the remains of a multitude of various animals which have existed. Among them there are found only a very small number who, to our knowledge, have analogous creatures like them now alive.

From that, can we logically conclude that the species which we find in the fossil state and for which there is no living individual exactly similar known to us does not exist any more in nature? There are still so many portions of the earth's surface into which we have not gone, so many others which people capable of making observations have not crossed except casually, and still so many others, like the different parts of the sea bottom, where we have few means for identifying the animals which live there, that these different places could well conceal species unknown to us.

If there are some species truly lost, this can only be, without any doubt, among the large animals which live in the dry parts of the earth where man, through the absolute dominion which he exerts, has been able to succeed in

destroying all the individuals of some species which he did not wish to preserve or to reduce to domesticity. Hence arises the possibility that the animals of Cuvier's genera palaeotherium, anoplotherium, megalonix, megatherium, mastodon and some other species of genera already known exist no longer in nature. However, that is only a possibility.

But the animals which live in the watery depths, above all in ocean waters, as well as all the small-bodied species living on the surface of the earth and breathing air are protected against the destruction of their species at the hand of man. Their reproductive rate is so large and the means which they have to save themselves from his pursuits or traps are such that there is no evidence that he can destroy the entire species of any of these animals.

Thus, it is only the large terrestrial animals which can be exposed to destruction of their species at the hand of man. Such an event could have taken place. But its reality has not yet been completely proved.

However, among the fossil remains which we find of so many animals who have existed there is a very large number belonging to animals for whom totally similar living analogues are unknown. And among these, most belong to the shelled mollusks, so that only the shells remain of these animals.

Now, if a number of these fossil shells reveal differences which do not permit us, according to accepted opinions, to regard them as analogous to neighbouring species which we know about, surely it must follow that these shells belong to species truly lost? Why, moreover, would they be lost, since man could not have brought about their

destruction? On the contrary, might it not be possible that the fossil individuals in question belong to species still existing but which have changed over time and have given way to species presently living which we find near by? The considerations which follow and our observations in the course of this work will make this assumption highly probable.

Every informed observer knows that nothing is constantly in the same state on the surface of the earth. In time, everything there undergoes various changes more or less constantly. High places are continuously eroded by the alternating actions of the sun, rain, and still other causes. Everything detached from there is drawn away toward places lower down. The beds of streams, rivers, even the seas vary in their shape, depth, and imperceptibly move. In a word, everything on the surface of the earth changes its position, shape, nature, and aspect, and even the climates of the earth's various regions are not any more stable.

Now, if, as I will be attempting to reveal, variations in the circumstances of living things, above all for animals, lead to changes in needs, habits, and ways of life, and if these changes give rise to modification of or developments in their organs and the shape of their parts, we must sense that imperceptibly all living bodies whatsoever must vary, especially in their shapes or external characteristics, although this variation will become noticeable only after a considerable time.

Thus, it is not astonishing if, among the numerous fossils which we find in all the dry places of the earth and which present to us so many animals which existed in

previous times, there are found so few whose living analogues we recognize.

By contrast, if there is anything which should astonish us it is to encounter among these numerous fossil remains of bodies once living some still having living analogues we do know about. This fact, which our fossil collections confirm, should lead us to assume that the fossil remains of animals whose living analogues we know about are the least ancient fossils. The species to which each of them belongs has undoubtedly not yet had sufficient time to vary in some of its forms.

Naturalists who have not perceived the changes which most animals experience with the passage of time, wishing to explain the facts relevant to the observed fossils, as well as to the known revolutions in different places on the surface of the earth, have assumed that a universal catastrophe took place with respect to the terrestrial globe and destroyed a large number of the species then in existence.

It is a pity that this convenient method of dealing with one's embarrassment when one wants to explain the operations of nature whose causes one been unable to grasp has no foundation except in the imagination which created it. It cannot be supported with a single proof.

Local catastrophes, like those which produce earthquakes, volcanoes, and other particular causes are sufficiently well known, and it is possible to observe the disorder which they bring about in the places which have experienced them.

But why should anyone assume, without proof, a universal catastrophe, when the better known progress of

nature is sufficient to provide a reason for all the facts which we observe in all its parts?

If one considers, on the one hand, that in everything which nature brings about, she make nothing abruptly and everywhere works slowly and by successive degrees and, on the other hand, that the particular or local causes of disorders, revolutions, displacements, and so on, can provide reasons for everything which we observe on the surface of the earth and are nonetheless subject to nature's laws and her general progress, one will recognize that it is not at all necessary to assume that a universal catastrophe came to knock over everything and destroy a large part of the very operations of nature.

That is enough on an issue which is readily comprehensible. Let us now consider the general features and the essential characteristics of animals.

Chapter FourGeneral Observations Concerning Animals

Generally considered, animals include living beings truly remarkable for faculties unique to them and at the same time worthy of our admiration and study. These beings, infinitely diversified in their forms, organic structures, and faculties, are capable of movement or of moving certain parts without the impetus of any communicated movement but by a cause which stimulates their irritability, a cause which, in some, is produced from within and, in others, is entirely outside them. For the most part, animals enjoy the ability to change their location, and they all possess eminently irritable parts.

We observe that in moving about some animals crawl, march, run, or jump, while others fly, raising themselves in the air and traveling through different spaces. Others, living in the depths of the waters, swim and transport themselves to different areas in the expanse of the surroundings waters.

The animals are not, like the plants, in a situation where they find within range right next to them the material on which they feed. Among animals, even those which live by seizing prey must go seek it out, follow it, and finally seize it. Thus, they must have a faculty of motion and even of moving around so as to be able to obtain the nourishment which they require.

Moreover, those animals which multiply by sexual reproduction do not offer sufficiently perfect hermaphrodites to enable them to meet their needs, and thus it is again

necessary that they can move around to put themselves in a situation where they can reproduce. For those animals which, like the oysters, cannot change their positions, the environmental surroundings must provide means for such movement.

Thus, these needs have the capacity to provide the faculty which the animals possess of moving parts of their bodies and of carrying out movements advantageous to their own conservation and that of their race.

In the second part we will look into the source of this astonishing faculty, as well as the cause of the most remarkable which we find among them. But in the meantime, so far as the animals are concerned, we will state that it is easy to recognize the following points:

(1) Some do not move or move their parts only as a consequence of their stimulated irritability. But they do not experience any feeling and cannot have any sort of will power. These are the most imperfect animals. (2) Others, apart from movements which their parts can undergo through their stimulated irritability, are susceptible to experiencing sensations and possess an intimate and very obscure feeling of their existence. But they act only through an interior impulse by a tendency which draws them to some object or other, so that their will power is always dependent and led on. (3) Still other animals not only experience movements in some parts as a result of their stimulated irritabilty, are susceptible to receiving sensations, and enjoy an inner feeling of their existence, but, in addition, have the ability to form ideas for themselves, although

confused, and to act by a determining will power, which is nevertheless subject to tendencies which carry them, once again, exclusively towards certain particular objects. (4) Finally, some other animals, the most perfect, possess to a high degree all the abilities of the preceding ones and enjoy, in addition, the power of forming for themselves clear or precise ideas of objects which have affected their sense and drawn their attention, of comparing and combining these ideas up to a certain point, and deriving from them judgments and complex ideas. In a word, they have the ability to think and to have a less captive will power, which permits them to vary their actions to a greater or lesser extent. In the least perfect animals, life is without energetic

movements, and irritability alone is then sufficient for vital movements. But since vital energy increases in proportion to the complexity of organic structures, there comes a limit where in order to provide sufficiently for the activities essential to vital movements, nature had to add to its means. And for that reason, she used muscular action to establish a system of circulation, from which followed the acceleration of the movements of fluids. This acceleration itself later grew in proportion to the muscular power which it required. Finally, since no muscular activity can take place without the action of nerves, the latter were everywhere found necessary to the acceleration of the fluids in question.

In this way nature was capable of adding to the irritability, once insufficient, muscular action and neural

influence. But this neural influence which gives rise to muscular action never brings it about by the path of feeling, something I hope to demonstrate in the second part. Later I will establish there that feeling is not at all necessary for the carrying out of vital movements, even in the most perfect animals.

Thus, the different existing animals are clearly distinguished from each other, not only by the particular features of their external shape, the consistency of their bodies, their size, and so on, but, in addition, by the faculties with which they are endowed. Some, like the most imperfect, find themselves reduced, in this respect, to the most limited state, not having any faculties other than those appropriate for life, not moving except through a power outside themselves; whereas, the others have progressively more numerous and more eminent faculties, to the point where the most perfect display a collection of faculties exciting our admiration.

These astonishing facts cease to surprise us when we first recognize that each acquired faculty is the result of a special organ or system of organs which gives rise to it and when later we see that from the most imperfect animal, which has no particular organ whatsoever and consequently no other faculty that those which belong to life itself, right up to the most perfect animal, the most richly endowed with faculties, the organic structure gradually gets more complex, in such a way that all the organs, even the most important, arise one after the other through the extent of the animal ladder, then successively perfect themselves by the modification which they undergo and which accommodates them to the state of their organic structure of which they are a part. Finally, through their combination in the most perfect animals they

present the most complex organic structures, which produce the most numerous and most eminent faculties.

Considering the internal organic structure of animals, the different systems which this organic structure presents throughout the extent of the animal ladder, and finally, the various specialized organs is thus the most important of all the ideas which must direct our attention in the study of animals.

If animals, looked upon as productions of nature, are living beings particularly astonishing for their faculty of movement, a large number of them are considerably more astonishing for their faculty of feeling.

But just as this faculty of movement is very limited in the most imperfect animals, where it is not at all voluntary and where it does not occur except through external stimuli, so it improves later more and more. It succeeds in originating within the animal itself and finishes by being subject to the animal's will power. Similarly the faculty of feeling is also very obscure and limited in the animals where it begins to occur, so that it develops progressively later and, having attained its main development, it manages to bring into existence in the animal the faculties which constitute intelligence.

In fact, the most perfect animals have simple and even complex ideas, passions, memory, a source of dreams, that is to say, they experience involuntary returns of their ideas, even their thoughts, and are up to a certain point capable of instruction. How admirable a result of nature's power this is!

To succeed in giving a living body the ability to move itself without the impetus of a communicated force, to

perceive objects beyond itself, to form ideas for itself, by comparing the impressions which it has recieved from them with those which it was able to receive from other objects, to compare or combine these ideas, and to produce judgments which are for it ideas of another order, in a word, to think, that is not only the greatest marvel which the power of nature has been able to achieve but, in addition, it is the proof that a considerable time has been taken up, for nature achieves nothing except step by step.

Compared to the lengths of time which we consider great in our ordinary calculations, it has undoubtedly required an enormous length of time and considerable variation in the sequence of circumstances for nature to have been able to lead the organic structure of animals to the degree of complexity and development where we see it in those who are the most improved. Thus, we justified in thinking that, if the analysis of these varied and numerous strata making up the exterior crust of the earth is an indisputable testament to its great age and if a consideration of the very slow but continuous displacement of the sea basin3, as evidenced by the numerous monuments to its passage which it has left everywhere, confirms once again the prodigious antiquity of the terrestrial globe, then a consideration of the degree of improvement which the organic structures of most animals must have reached helps, in its turn, to provide the highest quality evidence of this truth.

But in order to establish firmly the basis of this new proof, it will be necessary first to bring fully to light the proof relevant to the progress in organic structures themselves. It will be necessary to ascertain, if possible, the reality of this 3 Hydrogéologie, p. 41 ff.

progress. And finally it will be necessary to collect the best established facts in this matter and to indicate the means which nature possesses to give to all its productions the existence which they enjoy.

Let us note, meanwhile, that although it is generally acceptable, in referring to the beings which make up each kingdom, to indicate them under the general term productions of nature, it nevertheless appears that people have no clear idea associated with this expression. It seems that the prejudice against a particular origin prevents us from recognizing that nature possesses the ability and all the means to bring to life so many different beings on her own, continually to vary, although very slowly, the races of those which enjoy life, and to maintain throughout the general order which we observe.

Let us leave aside all opinions whatsoever concerning these important matters, and so as to avoid all imaginative errors, let us consult throughout the very acts of nature.

In order to be able to include, in our thinking, all existing animals and to place these animals in a perspective easy to grasp, it is appropriate to recall that all the natural productions which we can observe have been divided up by naturalists, for a long time now, into three kingdoms, under the denominations animal kingdom, vegetable kingdom, and mineral kingdom. By this division, the entities comprising each of these kingdoms have been set up comparatively, as if on the same line, although some have an origin very different from others.

For a long time now, I have found it more convenient to use another primary division, because it is appropriate for

making us more aware in general terms of all the entities which are the purpose of the enquiry. This, I separate all the natural productions comprising the three kingdoms which I have just pointed out into two main branches, as follows:

(1) organically structured bodies which are alive;(2) raw bodies without life.

Existing beings, or living bodies, like the animals and plants, make up the first of these two branches of the productions of nature. These beings have, as everyone knows, the ability to feed themselves, develop, reproduce, and are necessarily subject to death.

But what people do not so readily know, because prevailing hypotheses do not allow them to believe it, is that living bodies, as a result of their organic action and faculties, as well as the mutations which bring about in them organic movements, form themselves their own substance and secretory material (Hydrogéologie, p. 112). What people understand even less is that through their remains these living bodies give rise to the existence of all the composite materials, raw or inorganic, which we observe in nature. The various types of this material multiply in nature over time according to the circumstances of their location, through changes which they undergo imperceptibly and which simplify them more and more and lead, after a great deal of time, to the complete separation of the main elements composing them.

These are the various raw non-living materials, solid or liquid, which comprise the second branch of the productions of nature and which, for the most part, are known under the name minerals.

One can say that between raw materials and living bodies there is an immense hiatus which does not allow us to rank on the same line these two sorts of bodies, nor to undertake to link them by any modification, something which has been attempted but in vain.

All the known living bodies divide themselves neatly into two particular kingdoms, based on essential differences which distinguish animals from plants. In spite of what people have said about this, I am convinced that there is no longer a real point of subtle melding between these two kingdoms and that, consequently, that there are no animal-plants (something expressed in the word zoophyte) nor plant-animals.

The irritability in all or in certain parts is the most general characteristic of animals. That is more common than the faculty of voluntary movements and of feeling, more even that that of guiding oneself. Now, all the plants, without omitting even the plants called sensitive, nor those which move certain of their parts at the first touch or at the first contact with air, completely lack irritability. I have observed this point elsewhere.

We know that irritability is a faculty essential to the parts or some of them in animals. The actions of irritability are never suspended or destroyed so long as the animal is alive and the irritable part has not suffered any lesion in its organic structure. The effect of irritability consists of a contraction which the entire irritable part undergoes instantaneously on contact with a foreign body. The contraction stops with the cause and comes again, after the relaxation of the part, when new contacts happen to irritate it.

Now, nothing like this has ever been observed in any part of plants.

When I touch the extended branches of a sensitive (Mimosa pudica), instead of a contraction, I observe immediately in the attachments of the branches and disturbed petioles, a relaxation which allows these branches and petioles of the leaves to collapse, something which makes even the leaflets in this case droop down on one another. Once this drooping occurs, it is a waste of time to touch the branches and the leaves of the plant again; the effect does not recur. A relatively long time is needed, unless it is very hot, for the cause which can swell the articulations of the small branches and the leaves of the sensitive to raise again and extend all its parts and to deal with the sagging in such a way that it can happen again through contact or a light tremor.

I do not recognize in this phenomenon any connection with irritability in animals. But I do know that with plants during periods of growth, above all when it is hot, a great deal of elastic fluid is created, some of which is exhaled constantly. Thus I have concluded that in leguminous plants, these elastic fluids can gather particularly in the articulations of the leaves before dissipating and that they can there strain these joints and extend out the leaves or leaflets.

In such a case, the slow dissipation of the elastic fluids we are talking about, stimulated in the legumes by the arrival of night or the sudden dissipation of the same fluids stimulated in the Mimosa pudica by a small tremor gives rise, in the legumes generally, to the phenomenon known by the term plant sleep and in the sensitive to what people attribute

incorrectly to irritability4. Since, as a consequence of observations which I reveal further on and the conclusions I have drawn from them, it is not generally true that animals are feeling beings, all endowed, without exception, with the power of making voluntary acts and, consequently, having the option of moving at their own will, the definition which has been given of animals up to the present to distinguish them from plants is totally inappropriate. Thus I have already proposed to substitute for it the following, on the ground that it conforms more closely to the truth and is more appropriate for characterizing the beings which constitute both kingdoms of living bodies.

Definition of Animals

Animals are living organic bodies, endowed with permanently irritable parts; almost all of them digest the food with which they are nourished, and being subject to motion, some as a result of will power, whether free or dependent, and others as a result of their stimulated irritability.

4 In another work (Hist. nat. Des Végétaux, éditon de Déterville, vol.I, p. 202) I have dealt with some other similar phenomena observed in plants, for example, in hedysarum girans, dionoea muscipula, the stamens of the flowers in berberis, and so on, and I have revealed that the odd movements which we see in the parts of certain plants, principally in hot weather, are never the result of real irritability, or really of any of their fibres; they are rather sometimes hygrometic or pyrometric effects, sometimes the results of elastic relaxation which takes place under certain circumstances, and sometimes caused by swelling and weakening of parts, by the more or less rapid local accumulation and dissipation of invisible elastic fluids which the plants must excrete.

Definition of Plants

Plants are living organic bodies, never having irritable parts, not digesting anything, and not subject to motion, either by will power or by real irritability.

In accordance with these definitions, which are much more precise and better grounded than those which have been used up to now, we are aware that animals are preeminently distinguished from plants by the irritability which manifests itself in all their parts or some of them and by the movements which they can produce in these parts or which are stimulated there, thanks to their irritability, by external causes.

Undoubtedly it would be wrong to accept these new ideas on the basis of a simple introduction. But I think that all unprejudiced readers who take into consideration the facts which I will lay out in the course of this work and my observations concerning them will be unable to deny that they are better that the ancient views which I am replacing with them, because these ancient ideas are obviously contradicted by everything we observe.

Let us conclude these general opinions on animals with two quite curious considerations. The first concerns the extreme multiplicity of animals on the surface of the earth and those found in the depths of the waters. The second deals with the means which nature employs so that their number never harms the preservation of what she has produced or the general order which must prevail.

Among the two kingdoms of living bodies, the one which consists of animals appears much richer and more diverse than the other; at the same time it is the kingdom

which presents, in its organically structured products, the most admirable phenomena.

The surface of the earth, the depths of the waters, and, in some sense, even the air, are inhabited by an infinite number of various animals, whose races are so diversified and numerous that it is probable a large part of them will always elude our research. There is even more reason to think this given that the enormous extent of the waters, their depth in a great many places, and the prodigious fecundity of nature in the smallest spaces will undoubtedly always be an almost invincible obstacle to the advancement of our understanding of the subject.

For instance, one class of invertebrate animals by itself, the insects, in the number and the diversity of the objects which it includes, is equivalent to the entire plant kingdom. The class of polyps is probably much more numerous still. But we will never be able to congratulate ourselves that we know the total number of animals making up that class.

As a result of the extreme multiplication of small species, above all of the most imperfect, the quantity of individuals could injure the preservation of races and of the progress acquired by the improvement in organic structure, in a word, of the general order, if nature had not taken precautions to restrict this multiplication within limits which it can never cross.

Animals eat one another, except those which live on plants. But the latter run the risk of being eaten by carnivorous animals.

We know that the strongest and the best armed are the ones which eat the more feeble and that the large species devour the smaller ones. However, individuals of the same race rarely eat each other. They make war on other races.

The multiplication of the small animal species is so great and the renewal of their generations so quick that these small species would make the earth uninhabitable for others if nature had not placed a limit on their prodigious reproduction. But since they serve as prey for a multitude of other animals, since the length of their lives is very limited, and since cooler temperatures kill them off, their quantity is always maintained at just the right proportions for the preservation of their races and of the others.

As for the larger and stronger animals, they would be in a position to become dominant and to threaten the preservation of many other races if they were able to reproduce in very large numbers. But their races prey on each other and they reproduce only slowly and in small numbers at any one time. This fact once again preserves the equilibrium of the species at the right level.

Finally, man alone, considered apart from everything unique to him, seems able to reproduce indefinitely. For his intelligence and his methods protect him from seeing his numbers halted by the voracity of any of the animals. He exercises such a supremacy over them that instead of having to fear the largest and strongest animal races, he is able to destroy them, and every day he reduces their individual numbers.

But nature has given him numerous passions which, unfortunately, develop along with his intelligence, thus

placing a large obstacle to the extreme multiplication of the individuals of his species.

In fact, it seems that man himself is charged with constantly reducing the number of those like himself. For I am not afraid to state that the earth will never be covered with the population which she can feed. Several of its habitable parts will always be alternately very lightly populated, although the time periods for these fluctuating alterations for us will be infinite.

Thus, by wise precautions, everything perpetuates itself in the established order. Changes and constant renewals seen in this order are held within limits which they cannot cross. The races of living bodies all remain despite their variations. The progress acquired in the improvement of organic structure has lost nothing. Everything which seems disorder, reversal, anomaly constantly returns to the general order and even contributes to it. And everywhere and always the will of the sublime Author of nature and of all that exists is invariably brought about.

Now, before busying ourselves with a demonstration of the degradation and the simplification which exist in the organic structures of animals, as we proceed from the most complex to the simplest, following common practice, let us examine the present state of their distribution and classification, as well as the principles which have been used to establish these. Then it will be easier to recognize the proofs for the degradation in question.

Chapter FiveOn the Present State of the Distribution and

Classification of AnimalsFor the progress of Philosophical Zoology and for the

goal which we have in mind, it is necessary to consider the present state of the distribution and classification of animals, to examine how we have arrived at it, to recognize what the principles are to which we had to conform to establish this universal distribution, and finally to study what remains to accomplish to give this distribution the most appropriate character so as to make it depict the order of nature itself.

But to derive some benefit from all these matters, we must first determine the essential purpose of the distribution of animals and of their classification, because these two purposes have very different natures.

The purpose of a general distribution of animals is not only to obtain a convenient list to consult, but above all to have in this list an order which represents, as much as possible, the very order of nature, that is to say, the order which nature has very clearly characterized by the relationships which she has established between the animals.

The aim of a classification of animals, by contrast, is to furnish, with the help of lines of separation traced in various places in the general series of creatures, points where our imagination can stop so that we can more easily recognize each race which has already been observed, grasp the interconnections with the other known animals, and place in each group the new species which we succeed in discovering. This method compensates our weaknesses, makes our studies

and our understanding easier, and its use is indispensably necessary to us. But I have already shown that it is a product of art and that, despite any appearance to the contrary, it has no real connection with nature.

The proper determination of the interconnections between things will always invariably establish in our general distributions, first, the place of the large groups or the primary divisions and, second, that of the groups subordinate to the first and, finally, that of the species or the particular races which have been observed. Now, there you see the inestimable advantage for science of the knowledge of the interrelationships: since these interrelationships are the work of nature itself, no naturalist would ever have the power or, no doubt, the desire to change the results of a known interrelationship. The general distribution thus will become more and more perfect and compelling to the extent that our understanding of the interconnections advances with respect to the things which make up a kingdom.

The case is different with classification, that is to say, with the different lines of separation which we are concerned to trace from place to place in the general distribution, whether of animals or plants. In truth, as long as there will be spaces to fill in our distributions, because many animals and plants have not yet been observed, we will always find with these lines of separation that they seem to us created by nature itself. But this illusion will vanish to the extent that we continue to observe. And already have we not seen a sufficiently large number of them disappear, at least in the smallest groups, through the numerous discoveries of naturalists in roughly the last fifty years?

Thus, apart from the lines of separation which are the result of gaps which we have to fill, those which we will always be forced to create will be arbitrary and hence changeable, as long as naturalists do not adopt some conventional principle to regulate themselves when they draw such lines.

In the animal kingdom, we should consider as a conventional regulatory principle the fact that every class should be understood to consist of animals characterized by a particular structural system. The strict application of this principle is easy enough and presents only moderate inconveniences.

In fact, although nature does not move abruptly from one structural system to another, it is possible to establish some limits between each system, so that throughout nature there is only a small number of animals placed near these limits and in a position to raise some doubts about their true class.

The other lines of separation which sub-divide the classes are, in general, more difficult to fix, because they rest on less important characteristics and, for this reason, are more arbitrary.

Before examining the present state of the classification of animals, let me attempt to show that the distribution of living beings must form a series, at least with the large groups, and not a ramified network.

The classes must form a series in the distribution of animals

As human beings are condemned to go through all possible mistakes before recognizing one truth when they examine the facts which are relevant to it, people have denied that the productions of nature in each kingdom of living creatures were really in the position of being able to form a true series which follows a consideration of their interrelationships, and we have not wished to recognize any scale in the general arrangement, whether of animals or plants.

Thus, since naturalists have noticed that many species, certain genres, and even some families appear in a sort of isolation so far as their characteristics are concerned, several of them have imagined that the living creatures in one kingdom or the other, which according to their natural interconnections are closely related to or very distant from each other, are distributed like the different points of a geographical map or a globe. They consider the small and very pronounced series which have been called natural families as organized in the form of a network. This idea, which has appeared sublime to some moderns, is clearly a mistake. And it will undoubtedly disappear as soon as we have a more profound and more universal understanding of organic structure, above all when we distinguish what belongs to the influence of habitats and acquired habits from what is the result of more or less advanced progress in the composition or the perfecting of organic structures.

In the meantime, I am going to show that nature gives rise, with the help of a great deal of time, to the existence of

all animals and plants and has really established in each of these kingdoms a true ladder with respect to the growing complexity in the organic structure of these living beings, but that this ladder, which it is our concern to recognize in dealing with these things according to their natural interrelationships, only offers comprehensible gradations in the main large groups of the universal series and not in species, nor even in the genres. The reason for this point stems from the fact that the extreme diversity of circumstances in which the different races of animals and plants find themselves is not related to the increasing complexity in the organic structure among them, as I will show, and that gives rise in their shapes and exterior characteristics to anomalies or types of leaps which the increasing complexity in the organic structure could not have brought about by itself.

It is therefore a matter of proving that the series which makes up the animal ladder consists essentially in the distribution of the principle groups which make it up and not in the distribution of species, nor even in that of the genera.

The series which I am going to talk about could not therefore be established except in the placing of the large groups, because these groups which make up the classes and the large families each consist of beings in which the organic structure depends upon some particular system of essential organs.

Thus each distinct large group has its own particular system of essential organs. And it is these particular systems which are going to deteriorate from the one which shows the greatest complexity right to the one which is the simplest. But

each organ considered in isolation does not follow such a regular path in its deterioration. To the extent that the organ has less importance and is more susceptible to being modified by circumstances, it follows such a path even less.

In fact, the organs with little importance or inessential to life are not always similar to each other in their perfection or degradation, so that if we follow all the species of a single class, we will see that a particular organ in a particular species enjoys the highest degree of perfection, while some other organ which, in this same species, is much impoverished or very imperfect, is found very perfected in some other species.

These irregular variations in the perfection and the degradation of non-essential organs come up in those organs more subject than others to the influence of external circumstances. This influence brings with it similar variations in the shape and in the nature of the most external parts and gives rise to such a large and strangely organized diversity among species, that instead of being able to arrange them, like the large groups, in a unique series, simple and linear, in the form of a regularly graduated scale, these same species often form around the large groups of which they are a part, lateral branches, whose extremities display truly isolated points.

To modify each interior system of organic structure requires a more influential combination of circumstances and a much longer period of time than to modify and change the external organs.

Nevertheless, I notice that when circumstance demand, nature goes from one system to another, without making a

jump, provided that the systems are closely related. In fact, it is by this faculty that nature has managed to form all systems successively, going from the most simple to the most complex.

It is so true that nature has this faculty, that it moves from one system to another, not only in two different families when they are related by their interconnections, but even in a single individual.

The system of organic structure which include as organs of respiration real lungs are more closely related to systems which include gills than those which require tracheae. Thus, not only does nature move from gills to lungs in the neighboring classes and families, as a consideration of fish and reptiles shows, but it moves there even during the life of individuals themselves, who enjoy successively both systems. We know that frogs, in the imperfect tadpole state, breathe by gills; whereas, in their more perfect condition as frogs they breathe by lungs. We do not see anywhere nature passing from a system of tracheae to a pulmonary system.

Thus, it is true to say that there exists for each kingdom of living beings a unique and graduated series in the arrangement of the large groups, in conformity with the increasingly complexity in the organic structure and with the arrangement of things according to a consideration of the interrelationships and that this series, whether in the animal or plant kingdom, must offer at its front extremity the simplest and the least organized living creatures and finish with the most perfect in structure and faculties.

Such appears to be the true order of nature, and such is effectively what the most attentive observation and a

sustained study of all the features which characterize its progress clearly present to us.

Since the time when, in our distributions of the production of nature, we have felt it necessary to concern ourselves with the interrelationships, we are no longer masters at arranging the universal series as we please. The knowledge which we increasingly acquire of nature's progress, to the extent that we study the close or distant interrelationships which it has established, whether between objects or between their different groups, carries us along with it and forces us to conform to nature's order.

The first result obtained from the use of interrelationships in the placement of the large groups to form a general distributions is that the two extreme ends in the order must display the most dissimilar beings, because they are effectively the most distant so far as such interrelationships are concerned and, as a result, so far as organic structure is concerned. It follows from this that if one of the extremities of the order shows living beings developed in the most perfect way, those in which the organic structure is the most complex, the other extremity of the same order must necessarily show the most imperfect living creatures, that is to say, those in which the organic structure is the simplest.

In the general disposition of the known plants, according to the natural method, that is to say, according to the consideration of the interrelationships, as yet we understand reliably only one of the extremities of the order: we know that the cryptogram must be located at this extremity. If the other extremity is not established with the

same certainty, that stems from the fact that our knowledge of the organic structure of plants is much less advanced than what we understand about a large number of known animals. Consequently, so far as plants are concerned, we do not yet have a certain guide to determine the interrelationships between the large groups, of the sort that we have for recognizing those which exist between the genera and which form the families.

We do not encounter the same difficulty with the animals. The two extremities of their general series are determined in a definite way. For as long as we attach importance to the natural method and, as a result, to the consideration of the interrelationships, the mammals will necessarily occupy one of the extremities of the order, whereas, the infusorians will be placed at the other extremity.

Therefore, there is for animals, as well as for plants, an order which belongs to nature and which, like the things which this order brings into existence, results from the methods which nature has received from the Supreme Author of all things. It is nothing other than the universal immutable order which this Sublime Author has created in everything, together with the collection of general and particular laws to which this order is subject. By these means, which nature continues to use, it has given and perpetually is giving life to its productions. It varies them and renews them without ceasing, and in this way maintains the entire order which comes from these means.

We are going to see that this natural order which we were concerned successfully to recognize in each kingdom of living beings and of which we already possess various

sections in the well known families and in our best genera, is, so far as the animal kingdom is concerned, now determined in its entirely in a manner which leaves no room for anything arbitrary.

But the large number of the various animals which we have succeeded in understanding and the numerous insights which comparative anatomy has provided about their organic structure now give us the means of determining, in a definitive manner, the general distribution of all the known animals and of assigning a confirmed rank for the main divisions which we can establish in the series which they form.

That is what it is important to recognize and what will be truly difficult to dispute.

Let us now move on to an examination of the present state of the general distribution of animals and of their classification.

The Present State of the Distribution and the Classification of Animals

Since the purpose and the principles, whether of the general distribution of living beings or of their classification, have not been noticed when we concerned ourselves with these matters, the works of naturalists suffered for a long time from this imperfection of our ideas. The natural sciences were like all the others which we busied ourselves with for a long time before thinking about the principles which must form

the basis of the science and govern the work which goes on in it.

Instead of subjecting the classification necessary in each kingdom of living creatures to a distribution which nothing should interfere with, we thought only of classifying objects conveniently and in this way of subjecting their distribution to arbitrariness.

For example, since the connections between the large groups were very difficult to grasp among the plants, for a long time in botany we used artificial systems. They made convenient classifications easy to create, based on arbitrary principles. And each author made up new ones according to his fancy. Thus the distribution we need to establish among the plants, the one which, in a word, belongs to the natural method, was then always sacrificed. Only since we have understood the importance of the parts concerned with the fruit, and above all the preeminence which certain of those parts must have over the others, has the general distribution of plants started to progress towards perfection.

Since the case is not the same so far as animals are concerned, the general connections which characterize the large groups are, among themselves, a great deal easier to perceive. Also several of these groups have been recognized since the time when we first began to cultivate natural history.

In fact, Aristotle, at the start, divided the animals in two main groups or, according to him, two classes, as follows:

1. Animals with BloodViviparous quadrupedsOviparous quadrupedsFishBirds

2. Animals without BloodMollusksCrustaceansTestaceansInsects

This primary division of animals into two large groups was good enough, but the characteristic used by Aristotle in drawing it up was poor. This philosopher gave the name blood to the principal fluid in animals which is red in colour. Assuming that since all the animals which belong to his second class possessed only white or off white fluids, he therefore considered that they lacked blood.

Such was apparently the first sketch of a classification of animals. It is, at least, the oldest we know about. But this classification also gives the first example of a distribution in an sense reversed from the natural order, since we find in it a progression, although a very imperfect one, from the most complex to the simplest.

Since this time, people have generally followed this false direction with regard to the distribution of animals. And this has clearly held back our knowledge concerning the nature's march.

Modern naturalists believed that they were perfecting Aristotle's distinction when they gave to the animals of his first division the name red-blooded animals and to those of

the second division the name white-blooded animals. We are sufficiently aware now how much this characteristic is defective, since there are invertebrate animals with red blood (many annelids).

In my view, the fluids essential to animals cease to merit the name blood as soon as they no longer circulate in arterial and venous vessels. These fluids are then so degraded, so lacking in complexity or so imperfect in the combination of their principles, that we were wrong to link their nature to that of fluids which undergo a true circulation. Besides, attributing blood to a radiate or to a polyp means as much as attributing blood to a plant.

To remove all ambiguity or the use of any hypothetical consideration, in my first course of study which I carried out in the Museum, in the spring of 1794 (Year Two of the Republic), I divided all the known animals into two perfectly distinct groups:

Animals with backbones.Animals without backbones. I drew my students' attention to the fact that the

vertebral column indicates, in the animals which have it, the possession of a skeleton more or less perfect and of a structural plan relative to it; whereas, the lack of a vertebral column in the other animals not only clearly distinguishes them from the first ones, but announces that the structural plans on which they have been developed were all very different from those of the vertebrate animals.

From Aristotle up to Linnaeus, nothing very noteworthy has appeared concerning the general distribution of animals. But in the last century, some naturalists of

exceeding merit made a large number of particular observations concerning animals, mainly on a number of animals without vertebrae. Some revealed their anatomy with more or less detail; others provided an exact and detailed history of the changes in and the habits of a large number of these animals. As a result of their valuable observations, we have come to understand many facts of the highest importance.

Finally Linnaeus, a man of a superior genius and one of the greatest known naturalists, after having collected the facts and taught us to use great accuracy in the determination of characteristics for all the orders, gave us the following distribution for the animals

He distributed the known animals in six classes, on the basis of three stages or characteristics of their organic structure. Distribution of Animals Established by Linnaeus

Classes First Stage

I. Mammals II. Birds

A heart with two ventricles, red blood and warm

Second Stage

III. Amphibians (the Reptiles) IV. Fish

Heart with one ventricle, red blood, and cold

Third Stage

V. Insects A cold serum (in place of

VI. Worms blood)

Except for the inversion which this distribution manifests, like all the others, the four first divisions which it presents are now definitely fixed and will always be accepted by zoologists insofar as their position in the general series. And we see that it is the illustrious Swedish naturalist whom we have primarily to thank for this.

The case is not the same with the last two divisions of the distribution under discussion. They are poor and very badly arranged. Since they include the greatest number of known animals and those with the most diverse characteristics, they should be more numerous. It is therefore necessary to reformulate them and to substitute others for them.

Linnaeus, as we see, and the naturalists who followed him, gave so little attention to the need to multiply the divisions among the animals with a cold serum in place of blood (the animals without vertebrae) and those in which the characteristics present such a great variety, that they distinguished these numerous animals in only two classes, as follows: in insects and worms. As a result, everything which was not considered an insect, or alternatively, all animals without vertebrae which did not have articulated members were, without exception, included in the class of worms. They placed the class insect after the fish, and the class worms after the insects. The worms therefore formed, according to this distribution of Linnaeus, the last class of the animal kingdom.

These two classes are still found laid out, following this order, in all the editions of Systema naturae published

after Linnaeus. And although the essential problem of this distribution, so far as the natural order of animals is concerned, is evident and we cannot deny that Linnaeus' class worms is a sort of chaos in which things very different are found united, the authority of this scholar was so weighty among naturalists, that no one dared to change this monstrous class worms.

Intending to institute some useful reforms in this matter, I presented in my first course of study the following distribution for the animals without vertebrae, which I divided, not into two classes, but into five in the order given below: Distribution of Animals Without Vertebrae as Laid Out in My First Course of Study

1. Mollusks; 2. Insects

3. Worms

4. Echinoderms; 5. Polyps

These classes were made up then of some of the orders which Bruguiere had presented in his distribution of worms, an arrangement I did not adopt, and from the class insects, such as Linnaeus had described it.

However, towards the middle of Year Three of the revolution (1795), when the arrival of Cuvier in Paris directed the attention of zoologists to the organic structure of animals. I saw, with much satisfaction, the decisive proofs which he provided for the preeminence which must be given to the

mollusks over the insects, so far as concerns the rank which these animals must occupy in the general series, something which I had already carried out in my classes but which had not been viewed favorably on the part of naturalists of that capital city.

The change which I had made in this matter, from a sense of the inconvenience in Linnaeus' distribution which people followed, Cuvier endorsed perfectly through his explanation of the most reliable facts, among which several, in truth, were already known, but which had not yet attracted our attention in Paris.

Profiting then from the illumination which this scholar, since his arrival, has shed on all parts of zoology, and especially on the animals without backbones, which he called animals with white blood, I added successively new classes to my distribution. I was the first to institute them. But, as we are going to see, the classes of mine which were adopted were only accepted slowly.

No doubt, what interests authors is a matter of total indifference to science and also to those who study the subject. Nevertheless, there is a practical value in knowing the history of changes which the classification of animals has undergone in the past fifteen years. Here are those which I have effected.

To begin with, I changed the denomination of my class of echinoderms into that of Radiata, in order to unite in it the jelly fish and the genera which are related to them. This class, in spite of its utility and the necessity for it on account of the characteristics of these animals has not yet been adopted by the naturalists.

In my course for Year Seven (1799), I established the class crustaceans. At that time Cuvier in his Table of Animals, page 451, still included the crustaceans among the insects, and although this class is essentially distinct from the insects, nonetheless, the naturalists consented to adopt it only six or seven years afterwards.

The following year, that is to say, in my course for Year Eight (1800), I presented the arachnids as a special class, easy and necessary to distinguish. The nature of its characteristics were from that time on a certain indication of an organic structure peculiar to these animals, for it is impossible that an organic structure perfectly suitable to the insects, who all undergo metamorphoses, reproduce themselves only once in the course of their lives, and have only two antennae, two faceted eyes, and six articulated limbs, could give rise to animals which never undergo metamorphosis and which, in addition, present different characteristics which distinguish them from the insects. A part of this truth has since been confirmed by observation. However, this class arachnids has not yet been admitted in any work other than mine own.

Once Cuvier discovered the existence of arterial and venous vessels in different animals which people confused under the name worms with other animals very differently structured, I immediately used the implication of this new fact to perfect my classification. In my course for the Year Ten (1802), I established the class annelids, a class which I placed after mollusks and before crustaceans, something required by their acknowledged organic structure.

In giving a particular name to this new class, I was able to keep the ancient name worms for the animals which had always carried it and whose organic structure obliged me to distance them from annelids. Thus, I continued to place worms after insects and to distinguish them from radiata and polyps, with which people will never be authorized to unite them again.

My class annelids published in my course and in my Researches into Living Beings (p. 24) was around for several years without being accepted by naturalists. Nevertheless, for about the past two years, people are starting to recognize this class. But since people are of the opinion that they should change its name and to bring in the name worms for it, they do not know what to do with the creatures properly called worms, which do not have nerves, nor a system of circulation, and in this quandary, they are reuniting them with the class polyps, even though they are very different from them in their organic structure.

These examples of perfection first established in parts of a classification and later destroyed by others and later reestablished by the necessity and the pressure of things are not uncommon in the natural sciences.

In fact, Linnaeus combined several plant genera which Tournefort had previously separated, as one sees in his general polygonum, mimosa, justicia, convallaria, and plenty of others. And now the botanists are reestablishing the genera which Linnaeus had destroyed.

Finally, last year (in my course for 1807), I established among the animals without vertebrae a new tenth class, the infusorians, because after a sufficient examination of the

known characteristics of these imperfect animals, I was convinced that I had been wrong to include them among the polyps.

Thus, in continuing to collect the facts gained through observation and through the rapid progress in comparative anatomy, I instituted successively the different classes which now make up my distribution of the animals without vertebrae. These classes, ten in number, are arranged from the most complex to the simplest, as is the custom, as follows: Classes of Animals Without VertebraeMollusks CirrhipedsAnnelidsCrustaceansArachnidsInsectsWormsRadiataPolypsInfusorians

I will reveal in dealing with each of these classes that they constitute the necessary divisions, because they are based on a consideration of the organic structure and that, although it may be or indeed must be the case that we find in the vicinity of the limits to the classes some races, in one way or another, half way or intermediate between two classes, these divisions offer everything which art can produce which is most helpful in this sort of endeavour. Thus, as long as our main concern is an interest in science, people will not be able to do without acknowledging them.

It will be noticed that, by adding to these ten classes which divide the animals without backbones the four classes recognized and fixed by Linnaeus among the animals with vertebrae, we will have for the classification of all known animals the fourteen following classes, which I am going once more to present in an order opposite to the natural order.

Vertebrate Animals

1. Mammals

2. Birds

3. Reptiles

4. Fish

Invertebrate Animals

1. Mollusks

2. Cirrhipeds

3. Annelids

4. Crustaceans

5. Arachnids

6. Insects

7. Worms 8. Radiata

9. Polyps

10. Infusorians

Such is the present state of the general distribution of animals, and such is the distribution of classes which have been established among them

It will be a matter now of examining a very important questions which appears never to have been explored or discussed. However, the solution to it is essential. Here it is.

Since all the classes which are part of the animal kingdom form necessarily a series of large groups according to the growing complexity or diminishing complexity in their organic structure, must we, in the arrangement of this series, proceed from the most complex to the simplest or from the simplest to the most complex?

We will try to give the solution to this question in Chapter VIII which brings this part of the book to a conclusion. But before that we must examine a very remarkable fact, most worthy of our attention, which can lead us to notice the march nature follows in giving its various productions the existence which they enjoy. I am going to talk about the remarkable degradation which is found in all organic structure, if one moves through the natural series of animals, beginning with the most perfect or the most complex and moving towards the simplest and the most imperfect.

Although this degradation is not nor can be finely demarcated, as I will reveal, it exists in the main groups so evidently and with a sustained consistency, even in the variations in the path, that it depends, no doubt, on some general law which it is important for us to discover and, consequently, to seek out.

Chapter Six

Degradation and Simplification in the Organic Structure from One Extreme to the Other of the Chain of Animal Life, Going from the Most Complex to the Simplest

Among the considerations of interest to Zoological Philosophy, one of the most important concerns the degradation and the simplification observed in the organic structures of animals, as we move from one extremity of the chain of animal life to the other, from the most perfect animals to those with the simplest organic structure.

Now, the question is whether this fact can be truly verified. For then it will strongly illuminate for us the plan nature has followed and will set us on the road to discovering several of the natural laws most important for us to understand.

I propose here to prove that the fact in question is reliable and the product of a constant natural law, which always works uniformly, but that a particular cause, easily recognizable, make the regularity of the results which this law ought to produce vary here and there throughout the entire extent of the chain of animal life.

To begin with, one is forced to recognize that the general series of animals, arranged in accordance with their natural affinities, displays a series of particular groups, resulting from the different systems of organic structure employed by nature, and that if these groups are themselves

organized in accordance with the decreasing complexity of organic structures, they form a real chain.

Then, it is noticeable that, in spite of the anomalies (whose cause we shall establish), from one extremity to the other of this chain there reigns a striking degradation in the organic structures of the animals which comprise it, and a proportional diminution in the number of faculties of these animals. The result is that, if at one end of the chain in question are the most perfect animals in all respects, then at the opposite end we necessarily see the simplest and most imperfect animals which can be found in nature.

Finally, one has reason to believe, through this analysis, that all the special organs are simplified progressively from class to class, are changed, become diminished and weaker gradually, and that they lose the place where they are concentrated, if they are of primary importance, and end up by being completely and utterly done away with, before having reached the opposite end of the chain.

True, the degradation I am talking about is not always a regularly modulated progression. For often some organ is missing or changes suddenly, and in its transformations, it sometimes assumes odd shapes which do not link up with any other to any recognizable degree. Again, often some organ disappears and reappears several times before being utterly done away with. But we are going to see that this could not have been otherwise, that the cause which creates organic structures progressively must have experienced various deviations in its products, because its products are often in the position of being changed by a foreign cause which works

on them with an efficacious power. Nonetheless, we will see that the degradation under discussion is no less real and progressive in all the examples wherever we have been able to see it.

If the cause which constantly tends to increase organic complexity was the only one which had influence on the animals' shape and organs, the increasingly complexity in organic structure would be very regular throughout in its progression. But things are not like this. Nature found herself forced to submit her work to the influence of circumstances which operate on it, and everywhere these circumstances made the products vary. That is the particular cause which brings about here and there in the course of degeneration which we are going to confirm the often bizarre deviations which it presents to us.

Let us attempt to clarify both the progressive degeneration in the organic structure of animals and the cause of the anomalies which the progress of this degeneration manifests along the series of animals.

It is evident that, if nature had brought to life only aquatic animals and if all these animals had always lived in same climate, the same sort of water, at the same depth, and so on, then without doubt one would have found in the organic structure of these animals a regular gradation, even nicely modulated.

But nature has not confined her power within such limits.

First, one must note that nature has varied considerably the conditions of the water itself: fresh, salt, tranquil or stagnant, running or constantly agitated, hot and cold, finally,

shallow and very deep, thus presenting special circumstances each of which has a different effect on the aq1uatic animals living there. Now, to a degree corresponding to their organic structure, the animal races found exposed to each of these conditions have undergone from them specific influences and thus have been diversified.

After nature had produced aquatic animals of all ranks and varied them remarkably with the help of the different circumstances given by the waters, those which she led gradually to live in the air, at first on the waters' edge and afterwards on all the dry parts of the earth were placed over time in circumstances very different from the first, conditions which so strongly influenced their habits and organs that the regular gradation which they ought to present in the complexity of their organic structure was remarkably changed, so that it is almost unrecognizable in plenty of locations.

These considerations which I have examined for a long time and which I will set out with reliable proofs, led me to present the following zoological principle, whose foundation seems to me to be safe from any challenge:

The progress in the complexity of organic structure in the general series of animals undergoes, here and there, anomalies brought about by the influence of environmental factors and of acquired habits.

In considering these anomalies, people have justified their rejection of the progression which clearly exists in the complexity of animals' organic structure and their refusal to recognize the progress which nature follows in her production of living bodies.

However, in spite of the apparent gaps (which I am going to point out), the nature's general plan and the uniform progress in her manner of working, although infinitely various in its means, are still very easy to make out. To succeed in that, one needs to look at the general series of known animals, first envisaging it in its totality and then in its large groups. One will see there the least doubtful proofs of the gradation which nature has followed in the design of organic structure, a gradation which the anomalies I have mentioned would never permit one to mistake. Finally one will observe that wherever extreme changes in the circumstances have not been at work, one finds this gradation perfectly modulated in the various sections of the general series to which we have given the name families. This truth becomes even more striking in the study of what we call species. For the more we observe, the more our specific distinctions become problematic, complicated, and minute.

Thus, the gradation in the design of animal organic structure will be a fact which we will not be able to cast doubts upon, since we will have provided detailed and reliable proofs of what has just been outlined. Now, since we are taking the general series of animals in the inverse order to the one nature herself followed in bringing them successively into existence, this gradation is then changed, for us, into a remarkable degradation which governs from one extreme to the other of the animal chain, except for the interruptions which result from objects we have yet to discover and those provided by anomalies produced by extreme environmental circumstances.

Now to establish by reliable facts the basis for the degradation in the organic structure of animals from one

extremity of their general series to the other, let us first glance at the total make up of this series. Let us consider the facts laid out before us, and later we will move on quickly to review the fourteen classes which are its main divisions.

In examining the general distribution of animals in the way that I have presented it in the previous section, whose totality is unanimously vouched for by zoologists, who only argue about the limits of certain classes, I call attention to a very evident fact which should be, by itself, already decisive for my purpose, as follows:

At one end of the series (the one which people conventionally consider the anterior extremity), we see animals most perfect in all respects, whose organic structure is the most complex; whereas, at the opposite end of the same series are found the most imperfect animals in nature, those whose organic structure is the simplest and which one suspects are hardly endowed with animal life.

This well acknowledged fact, effectively beyond argument, becomes the first proof of the degradation which I intend to establish. For it is the essential condition for that degradation.

Another fact which arises from a consideration of the general animal series and which provides a second proof of the degradation which governs in the organic structure from one extremity of that chain to the other is the following:

The first four classes of the animal kingdom display animals generally provided with a vertebral column, while the animals of all the other classes totally lack this feature.

We know that the vertebral column is the essential basis of the skeleton, which cannot exist without it, and that wherever a vertebral column is found, there is a more or less complete skeleton, improved to a greater or lesser extent.

We also know that the improvement of the faculties proves the improvement in the organs which give rise to them.

Now, although man is beyond ranking, because of the extreme superiority of his intelligence, so far as his organic structure is concerned, he surely exemplifies the greatest improvement which nature has been able to reach. Thus, the more an animal's organic structure approaches man's the more it is improved.

This being the case, I observe that the body of a human being possesses not only an articulated skeleton but also one which is everywhere the most complete and improved in all its parts. This skeleton strengthens man's body, provides numerous points of attachment for his muscles, and allows him to vary his movements almost infinitely.

With the skeleton appearing as the main part in the design of the organic structure in the human body, it is evident that all animals furnished with a skeleton have an organic structure more perfect that those who lack such a structure.

That is the reason why the invertebrates are more imperfect than the vertebrates and why, when we place the most perfect animals at the head of the animal kingdom, the general animal series displays a real degradation in organic structure, for after the first four classes, all the animals in

those which follow lack a skeleton and are, consequently, less perfectly structured organically.

But that is not all. Among the vertebrates themselves, the degradation in question is noticed again; later we shall see that we come across it among the invertebrates. Thus this degradation is a consequence of the constant plan which nature follows and at the same time a result of the order we are following (but inversely). For if we were to follow the order itself, that is to say, if we moved through the general series of animals going up it from the most imperfect right to the most perfect of them, rather than a degradation in the organic structure, we would find a growing complexity, and we would see successively the animal faculties increasing in number and improvements. Now, to prove throughout the degradation in question, let us at this point quickly move through the different classes of the animal kingdom.

MAMMALSAnimals with mammary glands, having four

articulated limbs and all the essential organs of the most perfect animals; with hair on some parts of the body

The mammals (mammalia, Lin[aeus]) must obviously be located at one of the extremities of the animal chain, at the one which displays the most perfect animals, the most rich in organic structure and faculties. For it is uniquely among them that we find those having the most fully developed intelligence.

If the improvement in the faculties establishes the improvement of the organs which give rise to them, as I have already said, in that case all the mammals, who are truly viviparous, therefore have the most improved organic

structure, because it has been recognized that these animals have more intelligence, more faculties, and a more perfect combination of senses than all the others. In addition, there are those of them whose organic structure comes closest to that of human beings.

Their organic structure displays a body strengthened in its parts by an articulated skeleton, more generally a complete one in these animals than in the vertebrates of the three other classes. Most mammals have four articulated limbs, extensions of the skeleton. And all have a diaphragm between the chest and the abdomen, a heart with two ventricles and two auricles, warm red blood, free standing lungs contained in the chest, into which all the blood passes before being sent to other parts of the body. Finally, these are the only viviparous animals, for they are the only one in which the fetus, enclosed in its layers, nevertheless always communicates with its mother and develops by relying on her materials, and the young, after their birth, are nourished, for some time yet, from the milk of her breasts.

Thus, the mammals must occupy the first rank in the animal kingdom, from the point of view of the improvement in their organic structures and the large number of faculties (Recherches sur les Corps vivans, p. 15), because after them we do not find any more true viviparous reproduction, lungs contained by a diaphragm in the chest taking in all the blood which must be sent to other parts of the body, and so on.

In truth, among the mammals themselves, it is quite difficult to differentiate what belong essentially to the degradation we are examining from what is produced by

environmental circumstances, ways of life, and long established habits.

However, we find even among them traces of the general degradation in organic structure, for those whose limbs are appropriate for seizing objects are more highly perfected than those whose limbs are only appropriate for movement. In fact, it is among the first that human beings, considered from the perspective of organic structure, are located. Now, it is evident that the organic structure of human beings is the most perfect and must be looked upon as the standard against which we must judge the improvement or the degradation of other organic structures in animals.

Thus, in the mammals, the three sections which divide this class (although unequally) display amongst them, as we are going to see, a perceptible degradation in the organic structure of the animals making them up.

First Section: Unguiculate Mammals have four limbs, claws which are flattened or pointed at the end of their digits but which do not surround the digits. These limbs are, in general, appropriate for seizing objects or at least hanging from them. Among these animals are found the animals with the most improved organic development.

Second Section: Ungulate Mammals have four limbs, and their digits are entirely covered at the extremities with a round horn called a hoof. Their feet are used only for walking or running along the ground, and are not capable of being used for clambering up trees or seizing an object or prey, or to attack and rip other animals. They feed themselves only on plant life.

Third Section: Exungluate Mammals have only two limbs, and these limbs are very short, flattened, and shaped for swimming. Their digits, surrounded with skin, have neither claws nor hooves. Of all the mammals, these are the ones whose organic structure is the least perfect. They do not have a pelvis nor rear feet; they swallow without preliminary chewing; finally, they habitually live in water, but they come to the surface to breathe air. They have been given the name cetaceans.

Although amphibians also live in water, from which they emerge from time to time to crawl around the shoreline, they actually belong to the first section of the natural order and not to the one which includes the cetaceans.

From now on, we see that it is necessary to differentiate between the degradation which comes about from the influence of the habitual environment and acquired habits and that which is the result of a less advanced progress in improvement or in the complexity of organic structure. Also, one has to be careful about descending into consideration of detail, because, as I will show, the environments in which animals typically live, the specific locations they inhabit, patterns of behaviour enforced by circumstances, ways of life, and so on, have a large power of modifying the organs. Thus, one could attribute to the degradation we are discussing shapes of parts which are really due to other causes.

It is evident, for example, that the amphibians and the cetaceans, living habitually in a dense medium, where well developed limbs would only be able to interfere with their movements, must have only very shortened limbs, that it is

only as a result of the influence of the water impeding movements of very long limbs with solid interior parts, that they necessarily are made the way they really are, and that consequently these animals owe their general form to influences of the environment in which they live. But with respect to the degradation which we are seeking to recognize in the mammals themselves, the amphibians must be distant from the cetaceans, because their organic structure is much less debased in its essential parts. It requires that we bring them close to the order of unguiculate mammals, whereas, the cetaceans must form the last order of the class, since they are the least perfect mammals.

We are going to move on to the birds. But before that, I should note that between the mammals and birds there is no merging. There exists a gap to fill. Undoubtedly, nature has produced animals which almost fill up this gap and which must form a specific class, if they could be known, either in the mammals or in the birds, according to their systemic organic structure.

This has just been acknowledged by the recent discovery of two types of animals from New Holland, as follows:

Ornithorhyncus

EchidnesMonotremes, Geoff[roy].

These animals are quadrupeds, without mammary glands, embedded teeth, or lips; they have only one orifice for the genital organs, excrement, and urine (a cloaca). Their bodies are covered with hair or bristles.

These are not mammals at all, for they do not have mammary glands and are very obviously oviparous.

They are not birds, for their lungs are not pierced and they do not have limbs shaped into wings.

Finally, they are not reptiles, for their heart with two ventricles necessarily distances them from the reptiles.

Thus, they belong to a special class. BIRDS

Animals without mammary glands, with two feet and two arms shaped into wings; feathers cover the body.

The second rank obviously belongs to the birds, for if we do not find in these animals such a large number of faculties and as great an intelligence as in the animals of the first rank, they are the only ones except for the monotremes, who have, like the mammals, a heart with two ventricles and two auricles, warm blood, a skull cavity entirely filled by a brain, and the trunk always contained in ribs. Thus, they have qualities exclusively in common with mammalian animals and, consequently, affinities which we cannot find again in any of the animals of the later classes.

But the birds, in comparison with the mammals, display in their organic structure a clear degradation, one which has nothing to do with the influence of any sort of circumstances. In effect, they basically lack mammary glands, organs possessed only by the animals of the first rank, which serve for a reproductive system not found in the birds or in any of the animals in the ranks which come after. In a word, they are essentially oviparous, for the system of truly viviparous reproduction, something unique to the animals of

the first rank, does not recur from the second rank on and does not reappear elsewhere. Their fetus, enclosed in an inorganic envelope (the shell of the egg), hardly communicates any more with the mother and can develop within the eggshell without feeding on her material.

The diaphragm which in the mammals completely separates the chest from the abdomen (although more or less obliquely) ceases to exist in this group or is found only in very incomplete form.

There is nothing mobile in the vertebral column of birds, except the neck and tail vertebrae, because the movements of the other vertebrae in this column, not being found necessary for the animal, were not carried out and did not hinder the significant development of the sternum, which now makes such movements almost impossible.

In fact, the sternum of birds, which forms a place of attachment for the pectoral muscles which powerful movements, carried out almost continually, have made very thick and strong, has become extremely large and carinate in the centre. But this concerns the habits of these animals and not the general degradation which we are looking at. This last point is valid because the mammal which we call the bat also has a carinate sternum.

All the blood of birds passes once more through their lung before reaching the other parts of the body. Thus, they breathe completely by their lung, like the animals of the first rank. After them, no known animal has a similar system.

But here we see a very remarkable peculiarity relevant to the circumstances where these animals are found. Living more than the other vertebrates in the air, in which they rise

up almost all the time and cross in all kinds of directions, the habit they have acquired of puffing up air into their lungs in order to increase their volume and to make themselves lighter has made this organ stick to the side parts of the chest cavity and has put the air held there and rarefied by the heat of the location in a position to pierce the lung and the surrounding layers and to penetrate into all parts of the body, into the interior of the large bones, which are hollow, and right into the tubes of the large feathers.5 Nevertheless, it is only in the lung that the blood of the birds receives the influence of the air which it needs; for the air which penetrates into the other parts of the body has another purpose than respiration.

Hence, the birds, reasonably placed after the mammalian animals, display in their general organic structure a clear degradation, not because their lung presents a peculiarity which we do not find in the first animals and which is due, like their feathers, only to the habits they have acquired of ascending into the air, but because they no longer have the system of reproduction appropriate to the most perfect animals and have only the system of the majority of animals in the later classes. 5 If birds have their lungs pierced and their hair changed into feather as a

consequence of their habit of ascending into the air, people will ask me why the bats do not also have feathers and pierced lungs. I will reply that it seems to me probable that the bats have a systematic organic structure more perfect than that of the birds, and as a result a complete diaphragm which limits the enlargement of their lungs. Thus they were not able successfully to pierce their lungs nor to puff themselves up with air sufficiently so that the influence of this fluid, with effort reaching the skin, gives the horny material of the hair the faculty of branching out into feathers. In fact, in the birds, the air, once introduced right into the bulb of the hairs, changes their base into a tube and forces these very hairs to divide themselves up into feathers. This could not have happened with the bat, where the air does not penetrate beyond the lung.

It is very difficult to recognize among the birds themselves a degradation in the organic structure which is the purpose of our research here. Our knowledge of their organic structure is still too general. Thus, up to now, one or other of the orders of this class has been arbitrarily placed at the head of it, and the class terminated in the same way with the order which someone wished to select.

However, if we consider that aquatic birds (like those with webbed feet), the wading birds, and the gallinaceans have an advantage over all other birds, in that their young, in coming out of the egg, can walk and feed themselves, and, above all, if one attends to the fact that, among the webbed-footed birds, the penguins and king penguins, in which the almost featherless wings are only oars for swimming and are not capable of flight, a feature which makes these birds similar, in a way, to the monotremes and the cetaceans, then we will recognize that the palmipeds, wading birds, and gallinaceans must constitute the three first orders of birds and that the doves, passerines, birds of prey, rapaces and climbers, must form the four last orders of the class. Now, what we know about the habits of the birds of these last four orders tells us that their newborns, emerging from the egg, cannot walk or feed themselves on their own.

Finally, if following this analysis, the climbers make up the last order of birds, since they are the only ones which have two digits at the back and two in front. This characteristic, common to them and the chameleon seems to justify our placing them close to the reptiles.

REPTILESAnimals with only one ventricle in the heart and still

possessing a respiratory lung, but an incomplete one; their skin is smooth or furnished with scales.

In the third rank are placed, naturally and necessarily, the reptiles. They are going to provide us with new and greater proofs of the degradation in organic structure from one end to the other in the animal chain, starting at the most perfect animals. In fact, we do not see again in their hearts, which have only one ventricle, the structure which really belongs to the animals of the first and second ranks. Their blood is cold, almost like that of the animals of the later ranks.

Another proof of the degradation in organic structure of reptiles is presented to us in their respiration. First of all, these are the last animals to breathe by means of a real lung. For, after them, we do not see again in any of the animals in the following classes a respiratory organ of this sort (something I will try to establish in discussing the mollusks). Then, with the reptiles, the lung, in general, has very large chambers, proportionately fewer in number and already much simplified. In many species, this organ is missing in the early ages and finds itself then replaced by gills, a respiratory organ which we never find in the previous ranks. Sometimes here we find the two sorts of respiratory organs mentioned simultaneously in the same individual.

But the greatest proof of the degradation concerning the respiration of reptiles is that there is only one part of their blood which goes through the lung, while the rest reaches the

parts of the body without having received the influence of respiration.

Finally, with the reptiles, the four limbs essential to the most perfect animals begin to be lost, and many of them (almost all the snakes) even completely lack them.

Apart from the degradation in the organic structure acknowledged in the form of the heart, the temperature of the blood, which is only just above that outside in the environmental surroundings, the incomplete respiration, the almost gradual simplification of the lung, we notice that the reptiles differ considerably among themselves. The result is that the animals in each of orders of this class display greater differences in their organic structure and in their exterior form than those of the two preceding classes. Some live habitually in the open air, and among them, those which do not have legs can only crawl. Others live in water or at the water's edge, moving back, sometimes into the water and sometimes into open places. There are some which are covered in scales and others which have a bare skin. Finally, although they all have a heart with one ventricle, in some there are two auricles and in others only one. All these differences are relevant to environmental circumstances, ways of life, and so on, circumstances which, undoubtedly, have a more powerful influence on an organic structure which is still some way from the goal to which nature tends. These circumstances were not able to exert such an influence on those animals more advanced in their improvement.

Thus, the reptiles are oviparous animals (even those whose eggs are enclosed in the womb of the mother), have a modified skeleton, very often very degraded, display a

respiration and a circulation less perfected than those of mammalian animals and birds, and all manifest a small brain which does not completely fill the skull cavity. Thus, they are less perfect than the animals of the two preceding classes and confirm, on their part, the increasing degradation in organic structure, as we move closer to the most imperfect animals.

Among these animals, apart from the modifications to the shape of their parts resulting from the circumstances in which they live, we notice, in addition, traces of the general degradation in organic structure. For in the last of their orders (in the batrachians), individuals in the early stages breathe by gills.

If we consider the lack of legs (which we see in the snakes) a consequence of degradation, then the ophidians would make up the last order of reptiles. But to accept this idea would be a mistake. In fact, the snakes are animals which, in order to conceal themselves, have acquired the habit of crawling right on the ground. Their bodies have attained a considerable length disproportionate to their size. Now, the long legs would have hindered their need to crawl and hide, and very short limbs, which could only have been four in number (since these are vertebrate animals) would not have been capable of moving the body. Thus, the habits of these animals made their limbs disappear. Nonetheless, the batrachians, which do have legs, display a more degraded organic structure and are closer to fish.

The proofs for the important idea I am setting down will be established with reliable facts. Consequently, they will always be beyond the challenges which people might like in vain to offer in opposition to them.

FISHAnimals breathing through gills, having a smooth skin

or covered with scales and the body furnished with fins. In following the course of this degradation in organic

structure and in the number of faculties manifested in the total collection of animals, we see that fish must necessarily be placed in the fourth rank, that is, after the reptiles. They have, in fact, an organic structure still less perfected than that of the reptiles, and thus, more distant from that of the most perfect animals.

Without doubt, their general shape, lack of a narrowing between the head and the body (to form a neck), and the different fins serving them in place of limbs result from the influence of the dense milieu in which they live and not from the degradation in their organic structure. But this degradation is no less real and impressive, as we can see by examining their interior organs. That structure is such that it forces us to assign fish a rank after that of the reptiles.

In fish we do not find any more the respiratory organs of the most perfect animals; that is, fish lack a true lung and in place of this organ have only gills or vascular pectinate folds, placed on the two sides of the neck or the head, a total of four on each side. The water which these animals take in by the mouth passes between the layers of gills, bathing the numerous blood vessels located there. Since this water is mixed with air or contains air in solution, the air, although in small amounts, works on the blood in the gills and brings about the benefits of respiration. Then the water goes out sideways through the gills, that is, by the holes opened up on the two sides of the neck.

Now, note that this is the last time that a respiratory fluid will enter by the animal's mouth to reach the respiratory organ.

These animals, as well as those of the later ranks, do not have a trachea, a larynx, a real voice (even those called grondeurs), eyelids on their eyes, and so on. Here we see organs and faculties lost, ones which we do not find again any more in the rest of the animal kingdom.

However, the fish still are a part of the group of vertebrate animals. But they are the last of it, and they bring to a close the fifth level of organic structure, being, along with the reptiles, the only animals which have the following: - a vertebral column;- nerves ending in a brain which does not fill up the skull;- a heart with one ventricle;- cold blood;- finally, an entirely internal ear.

In addition, the fish display in their organic structure an oviparous reproductive system. They have a body without mammary glands, a body shaped very appropriately for swimming, fins which are not completely analogous to the four limbs of the most perfect animals, a very incomplete and remarkably modified skeleton (barely outlined in the last animals of this class), a single ventricle in the heart, cold blood, gills in place of a lung, a very small brain, a sense of touch incapable of understanding the shape of bodies, and apparently without a sense of smell, because odours are transmitted only through the air. It is obvious that these animals, for their part, strongly confirm the degradation in

organic structure which we have undertaken to follow through the full extent of the animal kingdom.

Now we are going to see that the main division of fish shows us, in the fish called bony, the most improved among them, and in the fish called cartilaginous, the least improved. These two points confirm, within this very class, the degradation in the organic structure. For the cartilaginous fish with their soft cartilaginous parts designed to make their bodies stronger and to make their movements easier show us that among them the skeleton ends, or rather that with them nature started to sketch out the skeleton.

As we still follow the order in the direction opposite to that followed by nature, the eight final genera of this class must include the fish whose brachial openings, without an operculum or a membrane, are only holes on the side or under the throat. Finally, the lampreys and the hag fish must come at the end of the class, because these fish are extremely different from all the others on account of the imperfection of their skeletons, and their bare viscous bodies, lacking lateral fins, and so on.

Observations on the VertebratesAlthough the vertebrate animals manifest among

themselves great differences in their organs, all their organic structures appear to be formed on a common plan. As we go up from the fish to the mammals, we see that this plan has been improved from class to class and that it has stopped completely only in the most perfect mammals. But we also notice that in the course of its improvement, this plan has undergone numerous modifications, some even very significant, on account of the influence of the environmental

conditions of the animals, as well as of the habits which each race has been compelled to acquire according to the circumstances in which it found itself.

Hence, we notice, on the one hand, that if the vertebrate animals are very different from one another in the condition of their organic structure, the reason is that nature began to carry out her plan for them only in the fish, later improved it in the reptiles, brought it closer to its completion in the birds, and finally succeeded in bringing it completely to a conclusion only in the most perfect mammals.

On the other hand, we cannot avoid the recognition that, if the improvements in the planned organic structure in vertebrates do not illustrate everywhere, from the most imperfect fish right up to the most perfect mammals, a regular modulated gradation, the reason is that the work of nature has often been changed, thwarted, and even turned away from its direction, by the influences which remarkably different, even contrasting circumstances have exerted on the animals exposed to them in the course of a long succession of generations.

Disappearance of the Vertebral ColumnAt this point of the animal ladder, we find the vertebral

column completely done away with. Since this column is the basis for all true skeletons and since this framework of bone constitutes an important part of the organic structure of the most perfect animals, all the invertebrate animals we are going to examine in succession thus have an organic structure even more degraded than it is in the four classes which we have just reviewed. Also from now on, the supports for muscular action will not be placed any more on interior parts.

Moreover, none of the invertebrate animals breathes by lungs with chambers or has a voice (and thus an organ for this faculty). Finally, they appear, for the most part, to lack real blood, that is, the essentially red fluid in the vertebrates which derives its colour only from the intensity of its animalisation and, above all, which establishes a real circulation. Surely it would be an abuse of language to give the word blood to the colourless thin fluid which moves slowly in the cellular substance of polyps? Will it then be necessary to assign a similar name to the sap in plants?

In addition to the vertebral column, in invertebrates is also lost the iris, which characterizes the eyes of the most perfect animals. For, among the invertebrate animals, those with eyes do not have them clearly equipped with irises.

Similarly, the kidneys are found only in the vertebrate animals, fish being the last ones in which we still encounter this organ. From here on, there is no more spinal marrow, no more large sympathetic nerve system.

Finally, a very important observation to note is that in the vertebrates, and mainly towards the end of the animal scale which displays the most perfect animals, all the essential organs are isolated, or each one has an isolated location in as many particular spots. We will soon see that the reverse of this has taken place, as we move towards the other end of the same scale.

It is thus evident that the invertebrate animals all have a less perfect organic structure than those which possess a vertebral column; the organic structure of mammals displays a vertebral column, a feature which indicates the most perfect

animals with respect to all the affinities, and is, without dispute, the true pattern of the most perfect organic structure.

Let us see now if the classes and the large families which are part of the numerous series of invertebrate animals display also, in a comparison of their groups, an increasing degradation in the complexity and the perfection of the organic structure in the animals which constitute them.

INVERTEBRATE ANIMALSWhen we reach invertebrate animals, we enter an

immense series of different animals, the most numerous in nature, the most curious and the most interesting with respect to the affinities in the observable differences of organic structure and faculties.

One is convinced, by observing their condition, that to bring them successively into existence, nature proceeded gradually from simplest to the most complex. Now, since nature intended to reach a planned organic structure which would permit the greatest improvement (that of the vertebrate animals), a plan very different from the one which she was probably forced to create to reach that goal, one senses that among these numerous animals we should run into not a single system in which the organic structure is improved progressively but various very distinct systems, each of which must have come about at the point where each organ of primary importance started to come into being.

In fact, when nature succeeds in creating a special organ for digestion (as in the polyps), for the first time she gave a particular and constant form to the animal furnished with it. The infusorians, where she started it all, could not possess either the faculty which this organ provides or the

style and shape of its organic structure in order to develop its functions.

Later, when nature established a special organ for respiration, as she varied this organ to improve it and to accommodate it to the environmental circumstances of the animals, she diversified the organic structure according to what the existence and the development of the other special organs successively required.

When, after that, nature succeeded in producing the nervous system, it was at once possible to create a system of muscles, and from then on it was necessary to have strong points of attachment for the muscles, the paired parts making up a symmetric form. The result of that was different types of organic structure, because of the environmental circumstances and the acquired parts, which could not have arisen previously.

Finally, when nature had attained sufficient movement in the fluids contained by the animal, so that the circulation could be organized, that once again resulted in important particular features in the organic structure which distinguishes it from organic systems in which circulation does not occur at all.

To notice the basis of what I have just laid out and to set out evidence for the degradation and the simplification in the organic structure (since we are following the order of nature in the reverse direction), let us run quickly through the different classes of invertebrate animals.

MOLLUSKSAs one goes down the graduated ladder which forms

the series of animals, the fifth rank necessarily belongs to the mollusks. For although we place them a degree lower than the fish, because they have no vertebral column, these are nevertheless the best organized of the invertebrates. The breathe by gills, but very diversified ones, in their form and size, or in their location on the inside or the outside of the animal, according to the genera and the habits of the races which these genera include. They all have a brain, nerves which do not have ganglia, that is, which do not display a row of ganglions along the length of a longitudinal marrow, arteries and veins, and one or a several one-chambered hearts. These are the only known animals which possess a nervous system but not a spinal column or a longitudinal marrow with ganglia..

The gills basically destined by nature to make respiration work in the very depths of the sea had to undergo modifications in relation to their faculties and their forms in the aquatic animals who, in the course of reproducing individuals of their race, went out often to expose themselves to the air and, as with many of these races, to remain there habitually.

The respiratory organ of these animals became imperceptibly accustomed to the air. This is not a supposition. For we known that all the crustaceans have gills; however, we know of crabs (cancer ruricola) who live habitually on the earth, breathing the natural air with their gills. Finally, this habit of breathing air with gills became necessary for plenty of mollusks who acquired it. The habit

modified the organ itself, so that the gills of these animals did not require any more so many points of contact with the respiratory fluid and became stuck to the inner walls of the cavity which contains them.

As a result, we distinguish among the mollusks two types of gills.

Some are made up of a maze of vessels which move up onto the skin of an interior cavity which does not form any projection and which can only breathe air. We can call these air gills.

The others are the organs almost always projecting, inside or outside the animal, forming fringes or pectinate layers or thin cords, and so on, which cannot make respiration occur except with the assistance of fluid water. We can call these aquatic gills.

If differences in the habits of the animals have brought about changes in their organs, we can at this point conclude from this fact that, for the study of characteristics peculiar to certain orders of mollusks, it will be useful to distinguish those who have air gills from those whose gills cannot respire except in the water. But one way or the other, it is always a matter of gills, and it seems to us very inconvenient to state that the mollusks which breathe air possess a lung. Who is not aware how often the abuse of words and the false application of names have helped to distort objects and to throw us into error?

Is there such a great difference between the respiratory organ of the Pneumoderma, which consists of a maze or vascular threads spread over the top of an exterior skin and the vascular maze of snails which spreads across an interior

skin. The Pneumoderma, however, appears to breath only water.

Besides, let us examine for a moment whether there are affinities between the respiratory organ of mollusks which breathe air and the lungs of vertebrate animals.

The characteristic property of the lung is to consist of a specific spongy mass, composed of more or less numerous cells, in which the natural air always moves, at first through the mouth of the animal, and from there through a more or less cartilaginous canal, called the trachea, which generally is divided into networks called bronchia, which end up in the cells. The cells and the bronchia are alternately filled with and emptied of air as a result of the successive swelling and collapse of the bodily cavity containing the mass of the organ. Consequently, it is a specific feature of the lung that it presents distinct and alternating inhalations and exhalations. This organ can survive only with direct contact with the air and becomes powerfully irritated by contact with water or any other material. It is thus of a different nature from the branchial cavity of certain mollusks which is always unique, which displays no distinct inhalation and exhalation and no alternating swelling and collapsing, which never has a trachea or bronchi, and in which the respiratory fluid never enters by the animal's mouth.

A respiratory cavity which displays neither trachea nor bronchi and no alternate swelling and collapsing, in which the respiratory fluid does not enter by the mouth, and which adapts itself, sometimes to the air, sometimes to the water, would not be capable of being a lung. To mix such different

objects up with the same name is not to advance science but to embarrass it.

The lung is the only respiratory organ which can give an animal the vocal faculty. After the reptiles, no animal has a lung; hence, none has a voice.

I conclude that it is not true that there are mollusks which breathe by a lung. If some breathe natural air, certain crustaceans do the same, as well as all the insects. But none of these animals has a true lung, so long as we do not give the same name to very different objects.

If the mollusks, because of their general organic structure, inferior in its improvements compared to fish, also establish, for their part, the progressive degradation which we are examining in the animal chain, the same degradation among the mollusks themselves is not so easy to determine. For among the very numerous and very diversified animals of this class, it is difficult to separate what belongs to the degradation in question and what is the product of the places where these animals live.

In truth, the two unique orders dividing the numerous class of mollusks very clearly contrast with each other in the importance of their distinct characteristics. The animals of the first of these orders (the cephalid mollusks) have a very distinct head, eyes, jaws or a proboscis, and reproduce by mating.

By contrast, all the mollusks of the second order (the acephalid mollusks) have no head, eyes, jaws, oral proboscis, and never reproduce by mating.

Now, one cannot deny that the second order of mollusks is inferior to the first with respect to an improved organic structure.

However, it is important to consider that the lack of head, eyes, and so on, in the acephalid mollusks is not uniquely the result of the general degradation in organic structure, since in the lower ranks of the animal chain, we find once more animals with a head, eyes, and so on. But it seems here that this is one of those deviations in the progressive improvements in organic structure produced by circumstances and, consequently, by causes foreign to those which gradually increase the complexity of organic structure in animals.

In considering the influence of the use of organs (the influence of an absolute absence of use and of constant use), we will see, in fact, that a head, eyes, and so on would have been particularly useless to the mollusks of the second order, because the great development in their mantle would not have permitted these organs any use whatsoever.

In conformity with that natural law which wills that all organs continually unused imperceptibly deteriorate, wither up, and finally disappear completely, we find the head, eyes, jaws, and so on, done away with in the acephalid mollusks. We will see elsewhere plenty of other examples of this.

In the invertebrate animals, since nature did not find in the interior parts points of attachment for muscular movement, she substituted, in the mollusks, the mantle with which she has furnished them. Now, this mantle in mollusks is stiffer and more compressed, the more these animals move about and the more they have only this mantle to assist them.

Thus, in the cephalid mollusks, where there is more movement than in those who do not have a head, the mantle is narrower, thicker, and stiffer. Among these cephalid mollusks, those which are bare (without shells) have in their mantle an additional breast plate even stiffer than the mantle itself, which makes the movements and the contractions of the animal (slugs) considerably easier.

But if instead of following the animal chain in the reverse order to nature's, we move through it from the most unimproved to the most improved, then it would be easily perceived that nature, just at the point of starting the plan of the organic structure of vertebrate animals, was forced, in the mollusks, to abandon the use of a shell or horny covering for the points of attachment for muscular action and that, as nature prepared to bring these points of attachment into the interior of the animal, the mollusks were placed, in some way, at the transition point in the system of organic structure. Consequently, having nothing more than feeble means of moving around, they execute these movements only remarkably slowly.

CIRRHIPEDESAnimals without eyes, breathing by gills, furnished

with a mantle and articulated arms with a horny skin. The cirrhipedes, for whom we as yet know only four

genera6 must be considered as forming a special class, because these animals cannot be included in the group of any other class of invertebrate animals.

6 The Anatifa, Balanus, Coronula and Tubicinella.

They are like the mollusks on account of their mantle, and one has to place them immediately after the acephalid mollusks, since, like them, they lack heads and eyes.

However, the cirrhipides cannot be included in the class of mollusks. For their nervous system displays, like the animals of the three classes which follow, a longitudinal marrow with ganglia. In addition, they have articulated arms with a horny skin and several pairs of transverse jaws. Thus, they are in a rank below that of the mollusks. The movements of their fluids takes place through a real circulation, with the help of arteries and veins.

These animals are established on marine bodies and consequently do not move around. Thus, their main movements are limited to those of their arms. Now, although they have a mantle like the mollusks, nature could not gain any help for movements of their arms from that and was forced to create on the skin of these arms points of attachment for the muscles which must move them. Thus, this skin is tough and rather horny, like the skin of crustaceans and insects.

ANNELIDSAnimals with elongated and ringed bodies, without

articulated limbs, breathing by gills, and with a circulatory system and a longitudinal marrow with ganglia.

The class of annelids comes of necessity after the class of cirrhipedes, because no annelid has a mantle. We are also forced to place them before the crustaceans because these animals do not have articulated limbs, because they must not interrupt the series of those who have them, and because their

organic structure does not permit us to assign them a rank after the insects.

Although these animals are, in general, as yet very little understood, the rank which their organic structure gives them proves that, so far as they are concerned, the degradation in organic structure continues to maintain itself. For, from this point of view, they are inferior to the mollusks, having a longitudinal marrow with ganglia. Moreover, they are also inferior to the cirrhipedes who have a mantle like the mollusks, and their lack of articulated limbs does not permit one to put them in a position where they break up the series of those manifesting this organic structure.

The elongated shape of the annelids, which they owe to their ways of living, whether buried in the damp earth or silt, or in the waters, where they live, for the most part, in tubes of different materials, which they leave and return to as they wish, makes them so like worms that all the naturalists up to this point have confused them with worms.

Their interior organic structure displays a very small brain, a longitudinal marrow with ganglia, some arteries and veins in which circulates a blood usually coloured red. They breathe through gills, sometimes external ones which project and sometimes internal ones hidden or not apparent.

CRUSTACEANSAnimals having a body and articulated limbs, a

crustaceous skin, a circulation system, and breathing by gills.

At this point we enter into the numerous series of animals in which the body and especially the limbs are

articulated and the integuments are crustaceous, horny, or coriaceous.

The solid or strong parts of these animals are all on the outside. Now, since nature created the muscular system very shortly before the first animals of this series and required points of attachment in solid parts to give the system energy, she was obliged to establish the method of articulations to make movement possible.

All the animals united by a similar method of articulation have been considered by Linnaeus and, following him, as forming only one single class, to which was given the name insects. But we finally recognized that this large series of animals displays several important divisions which it is essential to distinguish.

Also, the class of crustaceans, which has been confused with the class of insects (although all the ancient naturalists) had always separated it, is a division indicated by nature and essential to preserve. It must follow immediately after the annelids and occupy the eighth rank in the general series of animals. The analysis of its organic structure requires that. There is nothing at all arbitrary in this matter.

In fact, the crustaceans have a heart, arteries and veins, a transparent, almost colourless circulating fluid, and all breathe by true gills. That is incontestable and will always embarrass those who continue to rank them among the insects because they have articulated limbs.

If, because of their circulation and the respiratory organs, the crustaceans are clearly distinguished from the arachnids and the insects and if, consequently, their rank is clearly superior, nevertheless they share with the arachnids

and insects this lower feature of organic structure, with respect to the annelids, that is, they are part of the series of animals with articulated limbs, a series in which we see the circulation system going away and disappearing. Consequently, the heart, the arteries and veins, and even the respiration by the system of gills similarly is lost. Thus, the crustaceans confirm, in their turn, the degradation maintained in the organic structure, in the direction we are moving through the animal ladder. The fluid which circulates in their vessels is transparent and almost without substance, like that in the insects, and demonstrates once more this degradation with respect to them.

As to their nervous system, it consists of a very small brain and a longitudinal marrow with ganglia, a characteristic impoverishment of this system, which we see in the animals of the two preceding classes and the two which follow, for the animals of these classes are the last ones in which the nervous system is still present.

It is in the crustaceans that the last traces of the gill organ has been perceived. After them, it does not reappear in any animal.

ObservationsAt this point the existence of a true system of

circulation comes to an end, that is, a system of arteries and veins which makes up part of the organic structure of the most improved animals and which all the structures of all the preceding classes of animals possess. The organic structure of the animals which we are going to discuss is thus more imperfect still that that of the crustaceans, who are the last in which the circulation is well manifested. Thus, the

degradation in the organic structure continues in a clear manner, because to the further one moves ahead in the series of animals, all the features of resemblance between the organic structures of the animals we are considering and that of the most improved animals is successively lost.

Whatever the nature of the movement of fluids in the animals of the classes which we are going to go through, this movement works by less active means and always in a slower way.

ARACHNIDSAnimals breathing by narrow trachea, not undergoing

any transformation, and having at all times articulated limbs and eyes in their heads.

In continuing the order which we have followed up to the present, the ninth rank in the animal kingdom necessarily belongs to the arachnids. They have so many affinities with the crustaceans, that we will always be compelled to bring them close together and to place one immediately after the other. Nevertheless, they are clearly distinguished from the crustaceans. For they display the first example of a respiratory organ inferior to gills, because we do not ever come across it in the animals which have a heart, arteries, and veins.

In fact, the arachnids breathe only by stigmata and air trachea which are respiratory organs analogous to those of insects. But these trachea, instead of extending themselves throughout the entire body, like those in insects, are circumscribed in a small number of vesicles. This fact shows that nature concludes, in the arachnids, the method of respiration which she had to use before establishing gills, just

as she concluded, in the fish or in the last reptiles, what she had had to make sure of before she could form a true lung.

If the arachnids are clearly distinguished from the crustaceans, because they do not breathe at all by gills but by very narrow air trachea, they are also clearly different from the insects. It would be just as inconvenient to group them with the insects, whose classic characteristic they do not have, and from whom they differ especially in their interior organic structure as to mix up the crustaceans with the insects.

In effect, the arachnids, although having some important similarities to insects, are essentially distinct from them, for the following reasons:

(1) They never undergo a metamorphosis. They are born with the shape and all the parts which they must always retain and, consequently, they always have eyes in the head, articulated limbs, things arising out of the nature of their interior organic structure. In this they are very different from the organic structure of insects. (2) In the arachnids of the first order (pedipalp-arachnids) we begin to notice the traces of a system of circulation7. (3) With respect to their respiratory system, although of the same order as that of the insects, it is nevertheless very different, because their trachea,

7 "It is above all in the spiders that the heart is easy to observe. We see it beat through the skin of the abdomen in the non-hairy species. In lifting up this skin, we see a hollow organ, oblong, pointed at two ends, the anterior end pointing towards the thorax, on the sides of which two or three pairs of vessels can be seen leaving." Cuvier, Anatom. Comp. Vol. IV, p. 419.

limited to a small number of vesicles, are not made up of very numerous canals to the air extending throughout the animals' bodies, as we see with the trachea of insects. (4) Finally, the arachnids reproduce several times in the course of their lives, an ability which the insects lack. These considerations should suffice to enable us to

sense how faulty those distributions are which combine arachnids and insects in the same class, because their authors have taken into account only the articulations of the limbs of these animals and the more or less crustaceous skin covering them. That is a rather as if we took into account only the fact of the more or less scaly teguments of the reptiles and fish and thus combined them in the same class.

As for the general degradation in organic structure which we are looking into as we move through the entire animal scale, that is very clearly evident in the arachnids. Since these animals actually breathe through an organ less well developed with respect to structural improvements than the lung and even gills and have only the preliminary traces of a circulation which does not yet appear complete, they confirm, on their part, the continuing degradation in question.

This degradation is noticed even in the series of species brought together in this class. For the arachnids with antennae or of the second order are very different from others, are very inferior to them in the development of their organic structure and are very close to insects. Nonetheless, they differ from insects in that they do not undergo any transformation. Since

they never fly up into the air, it is very probable that their trachea do not generally extend to all parts of their bodies.

INSECTSAnimals undergoing transformations of form and

having, in the perfect state, two eyes and two antennae on the head, six articulated limbs, and two trachea extending throughout the entire body.

As we continue to follow the inverse order to nature's, after the arachnids necessarily come the insects, that is, this immense series of imperfect animals which have neither arteries, nor veins, which breathe by air trachea which are not limited, and finally which, being born in a state less perfect than that in which they reproduce, consequently undergo metamorphosis.

Once they reach their perfect condition, all the insects, without exception, have six articulated limbs, two antennae and two eyes on the head, and most of them then have wings.

According to the order we are following, the insects of necessity take up the tenth rank in the animal kingdom. For they are inferior in improvements to their organic structure to the arachnids, because they are not, like the latter, born in their perfect condition and they reproduce only once during the course of their lives.

Particularly among the insects we begin to notice that the organs essential to maintain life are distributed almost equally and most of them are situated throughout the extent of the body, rather than being isolated in particular places, as was the case in the most improved animals. This

consideration gradually loses its exceptions and becomes more and more striking in the animals in the later classes.

Nowhere, up to this point, is the general degradation in organic structure more manifest than in the insects, where that structure is inferior in improvements to that of the animals in all the preceding classes. This degradation even shows up between the different orders which naturally divide the insects. For those in the three first orders (Coleoptera, Orthoptera, and Neuroptera) have mandibles and jaws in their mouths. Those of the fourth order (Hymenoptera) begin to possess a sort of proboscis; finally those of the four last orders (Lepidopteres, Hemiptera, Diptera and Aptera) really have only a proboscis. Now, paired jaws do not turn up anywhere in the animal kingdom after the insects of the three first orders. With respect to wings, the insects of the six first orders have four of them, of which all or two alone serve for flight. Those of the seventh and eighth orders have only two wings, or their wings are aborted. The larvae of insects of the two final orders do have limbs and resemble worms.

It appears that insects are the last animals which display a clearly distinct sexual reproduction and which are truly oviparous.

Finally, we will see that the insects are infinitely remarkable for the details concerning what has been called their industry but that this alleged industry is not at all the product of any thinking, that is, of any combination of ideas on their part.

ObservationJust as the fish, among the vertebrates, display in their

general shape and in the anomalies relative to the progression

in complexity of organic structure, the results of the influence of their environmental habitat, so the insects, among the invertebrates, display in their form, organic structure, and transformations, the clear result of the influence of the open air in which they live and up into which most of them leap and habitually stay, like the birds.

If the insects had had a lung, if they had been capable of inflating themselves with air, and if the air which reaches all parts of their body had been able to rarefy itself there, like the air which goes into the bodies of birds, their hairs would have been changed, no doubt, into feathers.

Finally, if, among the invertebrate animals, it is astonishing to find so few affinities between the insects which undergo singular metamorphoses and the invertebrate animals of the other classes, one should draw attention to the fact that these are the only animals without vertebrae who leap up into the air and carry out progressive movements there. Then one will sense that quite special circumstances and habits must have produced results which are just as special.

The insects are close only to the arachnids in their interrelationships. And, in fact, both of them are, in general, the only animals without vertebrae which live in the air. But no spider has the ability to fly, and no arachnid likewise undergoes transformation. In dealing with influences of habits, I will show that these animals, because they were accustomed to stay on parts of the surface of the earth and to live in hidden places, must have lost some of the ability of insects and to acquire characteristics which clearly distinguish them from insects.

The Destruction of Several Organs Essential to the More Improved Animals

After the insects, it appears that there is quite a considerable gap in the series, which animals we have not observed remain to fill in. For in this position in the series, several organs essential to more improved animals suddenly are missing and are really done away with, because we do not find them again in the classes which remain for us to review.

The Disappearance of the Nervous SystemHere the nervous system (the nerves and their central

connection) effectively disappears completely and does not appear any more in any of the animals of the classes which follow.

In the most improved animals, this system consists of a brain which appears to serve to carry out of acts of intelligence, at the base of which is located the chamber of sensations, from which the nerves leave, as well as a dorsal spinal chord which sends other nerves out to the various parts.

In the vertebrates, the brain successively diminishes, and as its volume gets smaller, the spinal column becomes larger and seems to take its place.

In the mollusks, the first class of invertebrates, the brain still exists, but it does not have a spinal chord or longitudinal marrow with ganglia. Since the ganglia are rare, the nerves do not appear knotty.

Finally, in the five classes which follow, the nervous system, in its last stage, is reduced to a very small brain, hardly a trace, and a longitudinal marrow which sends nerves

to the parts. From that point on there is no isolated chamber for sensations, but a multitude of small places spread throughout the full length of the animal.

Thus, in the insects the important system of feeling ends, that system which, at a particular stage of its development, gives rise to ideas, which in its highest perfection can produce all intelligent acts, and which, finally, is the source where muscular action gets its power and without which sexual reproduction apparently cannot exist.

Disappearance of the Sexual OrgansAgain, here traces of sexual reproduction disappear

completely and, in fact, in the animals which are going to be listed, it is no longer possible to recognize the organs of a true fertilization. Nevertheless, we are going to find again in the animals of the two classes which follow, species with types of ovaries in oviform corpuscles which are taken for eggs. But I consider these alleged eggs, which can produce without prior fertilization as buds or internal gemmules. They create the link between internal gemmiparous reproduction and oviparous sexual reproduction.

The inclination of human beings for their own habits is so great that they persist, even against the evidence, to look at things always in the same manner.

This is the reason why botanists, accustomed to observe the sexual organs of a large number of plants, want all plants, without exception, to have similar organs. Consequently, several of them have made every imaginable effort, with respect to the plants cryptogames or agames, to discover stamens and pistils. And they have preferred to attribute to the plants arbitrarily and without proof functions

to those parts whose use they did not know rather than to recognize that nature knows how to reach the same goal by different means.

We were persuaded that every reproductive body is a seed or an egg, that is, a body which, in order to be reproductive, needs to undergo the influence of sexual fertilization. This point made Linnaeus state: Omne vivum ex ovo [All living things are from the egg]. But we now know very well plants and animals which regenerate themselves solely by bodies which are neither seed nor eggs and which, consequently, have no need for sexual fertilization. Thus, these bodies are shaped differently and develop in a different manner.

Here is the principle to which we must pay attention in order to assess the method of reproduction of any living body whatever.

Every reproductive corpuscle, whether plant or animal, which, without breaking through any enclosing material, grows longer and larger and become a plant or animal similar to the one which it came from is neither a seed nor an egg. It does not undergo any fertilization or hatch after having started to grow, and its formation has not required any sexual impregnation. Thus it does not contain an embryo enclosed in layers which must be broken through, as in the seed or the egg.

Now, follow attentively the developments of the reproductive corpuscles of algae, fungi, and so on, and you will see that these corpuscles only grow longer and larger so as to take on imperceptibly the form of the plant from which they issued forth. They do no break through any enclosing

material, as does the embryo of the seed or the one that contains the egg.

Similarly, if you follow the gemma or bud of a polyp, like the hydra, you will be convinced that this reproductive body only grows longer and larger, that it does not break through any exterior covering, in a word, that it does not hatch like a chicken or a silk worm coming from an egg.

Thus, it is clear that all reproduction of individuals does not take place by way of sexual fertilization and that where sexual fertilization does not bring it about, there is essentially no true sexual organ. Now, since, after the insects, we do not distinguish in the four classes of animals which follow any organ of fertilization, it appears that it is at this point in the animal chain that sexual reproduction ceases to exist.

Disappearance of the Organ for SightHere again, the organ for sight, so useful to the most

perfect animals, is entirely done away with. This organ, which started to be absent in a section of the mollusks, in the cirrhipedes, and in most of the annelids, and which is found again in the crustaceans, arachnids, and insects only in a very imperfect condition, with an extremely limited use (or none at all) does not reappear after the insects in any animal.

Finally, at this point also the head, that essential body part in the most perfect animals, the seat of the brain and almost all the senses, totally ceases to exist. For the bulge in the forward extremity of the body of some worms, like the Taenia, which is caused by the arrangement of their suckers, is neither the seat of a brain nor of organs of hearing, sight, and so on, because all these organs are lacking in the animals

of the classes which follow; the swelling in question cannot be considered a true head.

We see that at this stage of the animal scale, the degradation in organic structure becomes extremely rapid and that it makes one look ahead to the greatest simplification in the organic structure of animals.

WORMSAnimals with soft, long bodies, without a head, eyes,

articulated limbs, lacking a longitudinal marrow and a system of circulation.

We are here considering the worms, who do not have any vessels for circulation, for instance, those which we know about under the name intestinal worms, and some other non-intestinal worms, whose organic structure is just as imperfect. These are animals with a soft body, more or less elongated, not undergoing any metamorphosis, and all lacking head, eyes, and articulated limbs.

The worms must immediately follow the insects, come before the radiates, and occupy the eleventh rank in the animal kingdom. Among them we see starting nature's tendency to establish the system of articulations, a system which she has later completely developed in the insects, arachnids, and crustaceans. But the organic structure of worms is less perfect than that of insects, because they no longer have a longitudinal marrow, head, eyes, and real limbs. Thus, this organic structure compels us to put them after the insects. Finally, the new style in the shape which nature starts in them to establish a system of articulations and to move away from the radiating system in the parts proves that we must place the worms before the radiates themselves.

In addition, after the insects we lose the plan carried out by nature in the preceding classes, that is, this general animal shape which consists of an opposing symmetry in the parts, in such a way that each of the parts is opposite an entirely similar part.

In the worms, we no longer find this opposing symmetry in the parts, and we do not see again the radiating arrangement of the organs, both interior and exterior, which we notice in the radiates.

Since the time that I established the class of annelids, some naturalists have given the name worms to annelids themselves. Since they then did not know what to do about the animals in question, they combined them with the polyps. I leave it to the reader to judge what affinities and classic characteristics authorize us to combine in the same class a Tenia or an Ascaris with a Hydra or any other polyp.

Like the insects, several worms appear still to breathe by trachea, whose openings to the outside are s type of stigmata. But there is reason to believe that these limited and imperfect trachea are aquatic and not aerial, like those of insects, because these animals never live in the open air and are always either deep in water or bathed in the fluids which contain them.

No organ of fertilization is very distinct in them. Thus, I assume that sexual reproduction has no role with this animal. Nevertheless, it could be possible that, just as the circulation is hinted at in the arachnids, so sexual reproduction is sketched out in the worms. This seems to be indicated by the different shapes of the tail in the Strongylus.

But observation has not yet well established this reproduction in these animals.

What we see in some of the worms and what we take to be ovaries (as in the Tenia) appear to be only a mass of reproductive corpuscles which do not require fertilization. These oviform corpuscles are internal, like those in the sea urchin, instead of being external like those in the Coryne, and so on. The polyps display amongst themselves the same differences with respect to the position of the gemmules which they produce. Thus, it is plausible that the worms are internally gemmiparous.

Some animals which, like the worms, lack head, eyes, limbs and perhaps sexual reproduction, thus also establish, in their turn, the degradation maintained in the organic structure which we are looking into in the entire extent of the animal scale.

RADIATESAnimals with a regenerating body, lacking a head,

eyes, articulated limbs, with a mouth on the under surface, and a radiating arrangement in their internal and external parts.

Following the customary order, the radiates occupy the twelfth rank in the numerous series of known animals and make up one of the three last classes of invertebrate animals.

When we arrive at this class, we encounter in the animals included in it a style of general shape and arrangement of parts and organs, both external and internal, which nature has not used in any animals of the previous classes.

In effect, the radiates very clearly have in their internal and external parts a radiating arrangement around a centre or an axis which makes up a special shape which nature has not, up to that point, ever used. She began to sketch out such an arrangement only in the polyps, which, consequently, come after the radiates.

Nevertheless, the radiates make up in the animal scale a compartment very different from that of the polyps, so that it is no longer possible to confuse the radiates with the polyps any more than it is to group the crustaceans with the insects or the reptiles among the fish.

In fact, in the radiates not only do we still observe organs which appear destined for respiration (tubes or types of aquatic trachea), but we also see, in addition, special organs for reproduction, like types of ovaries in various shapes. Nothing similar is found in the polyps. Moreover, the intestinal canal of radiates is not generally a closed tube with only one opening, as in all the polyps. And the mouth, always low down or on the lower surface, manifests in these animals a special arrangement which is not at all the one which the polyps display in their general structure.

Although the radiates are truly curious and as yet little understood animals, what we know about their organic structure clearly indicates the rank to which I am assigning them. Like worms, the radiates are headless, eyeless, without articulated limbs, a system of circulation, and perhaps without nerves. However, the radiates come necessarily after the worms. For the latter have nothing in the arrangement of their interior organs which tends to a radiating shape, and it is among them that the style of articulations begins.

If the radiates lack nerves, they are then without the faculty of feeling and are no more than merely irritable. This seems to be confirmed by observations made on living star fish in which the arms have been cut off without their showing any sign of pain.

In many radiates fibres are still distinct. But can we call these fibres muscles, unless we are justified in stating that a muscle deprived of nerves is still capable of carrying out its functions? Do we not have, in plants, the example of the potential possessed by cellular tissue of being reduced to fibres without our being able to consider these fibres muscles? Every living body in which we make out fibres does not, it seems to me, have muscles just for this reason. And I think that where there are no more nerves, the muscular system no longer exists. There is reason to believe that in animals without nerves the fibres which we can still come across there possess, through their simple irritability, the faculty of producing movements which replace muscular movement, although with less energy.

In the radiates, not only does it appear that the muscular system no longer exists, but also that there is no more sexual reproduction. In fact, nothing gives evidence of that or even indicates that the small oviform bodies, whose mass make up what we call the ovaries of these animals, undergo fertilization (and are thus true eggs). This is all the more implausible when we find them equally in every individual. Thus, I consider these small oviform bodies to be internal gemmules already perfected, and their clumping together in special places is the method nature has prepared to arrive at sexual reproduction.

The radiates, confirm, in their turn, the general degradation in the organic structure of animals. For in this class of animals, we meet a new form and arrangement of parts and organs which are far distant from those of animals in the preceding classes. Moreover, they appear to lack feeling, muscular movement, and sexual reproduction. Among them, we see the intestinal canal cease to have two openings, the clusters of oviform corpuscles disappear, and the bodies become entirely gelatinous.

ObservationIt seems that in the very imperfect animals, like the

polyps and the radiates, the centre of movement of the fluids no longer exists except in the alimentary canal. There it commences to establish itself, and by the way of this canal the subtle ambient fluids mainly enter to stimulate movement in the containing fluids appropriate to these animals. What would plant life be, without external stimuli, and, by the same token, what would life be for the most imperfect animals without this cause, that is to say, without the heat and electricity of the environmental surroundings.

Undoubtedly, through a sequence of this sort employed by nature, first with a feeble energy in the polyps and later with greater developments in the radiates, the radiating form was acquired. For the subtle ambient fluids, by penetrating through the alimentary canal and expanding, must have, by means of a constantly renewed expulsion from the centre towards all the points on the circumference have given rise to this radiating shape in the parts.

This is the reason why, in the radiates, the intestinal canal, although still very imperfect (because very frequently

it only has one single opening) is nevertheless complicated with numerous radiating vasculiform and often branching appendixes.

No doubt, for the same reason in the soft radiates, like the jelly fish, and so on, we see a constant isochronous movement, a movement which very probably results from successive irregular movements in the masses of subtle fluids which penetrate into the interior of these animals and also the movements of these same fluids which escape after being spread throughout every part.

We should not say that the isochronous movements in the soft radiates are the consequences of their respiration. For after the vertebrate animals, nature does not manifest in any other animal alternating and measured movements of inhaling and exhaling. Whatever the respiration of radiates may be, it is extremely slow and goes on without perceptible movements.

POLYPSAnimals with a sub-gelatinous and regenerating body,

without any special organs, other than an alimentary canal with a single opening; a terminal mouth, together with radiating tentacles or a ciliate and rotating organ.

When we reach the polyps, we have arrived at the penultimate step of the animal scale, that is to say, at the penultimate class which it has been necessary to establish among the animals.

Here, the imperfection and the simplicity in the organic structure are very evident, so that the animals at this point

have hardly any more faculties and for a long time we had doubts about their animals nature.

These are gemmiparous animals, with a homogeneous body, usually gelatinous, very regenerative in their parts, not manifesting a radiating shape (something nature began in them) except in their radiating tentacles around their mouths. They have no other special organ except an intestinal canal with a single opening and, consequently, incomplete.

We can say that polyps are much more imperfect animals than those which are part of the preceding classes. For we do not find in them either brain, longitudinal marrow, nerves, special organs for respiration, vessels for circulation of fluids, nor ovaries for reproduction. The substance of their bodies is, in some way, homogenous, and made up of a gelatinous and irritable cellular tissue, in which fluids move slowly. Finally, all their internal organs are reduced to an imperfect alimentary canal, rarely folded back on itself or furnished with appendixes, looking in general like only a long sack, always with only one single opening serving simultaneously as a mouth and anus.

We can find no firm reason for claiming that in the animals in question, where we do not find a nervous system, a respiratory organ, muscles, and so on, these infinitely reduced organs nonetheless exist, but that they are spread out and dissolved in the general corporeal mass and equally distributed in all its molecules, instead of being collected together in particular places and that therefore, every point in their bodies could experience all sorts of sensations, muscular movement, will power, ideas, and thought. That would be a totally gratuitous assumption, without basis and probability.

Besides, with such an assumption, one could say that the hydra has in all the points of its body, all the organs of the most perfect animals, and as a result, that each point in the body of this polyp sees, hears, distinguishes odours, notices tastes, and so on, and in addition that it has ideas, forms judgments, and thinks, in a word, that it reasons. Each molecule of the body of the hydra or of every other polyp would be by itself a perfect animal, and the hydra itself would be an even more perfect animal than human beings, because each of its molecules would be of equivalent value, in the complement of its organic structure and faculties, to a complete individual of the human race.

There is no reason to refuse to extend the same reasoning to the monad, the most imperfect of known animals and then to stop the application of this reasoning to the plants themselves, which also enjoy life. Then one would attribute to each molecule of a plant all the faculties which I have just cited, but held within the limits relative to the nature of the living body of which that molecule is a part.

That is certainly not the point to which the results of the study of nature lead. This study teaches us, by contrast, that everywhere where an organ ceases to exist, the faculties which depend upon it also cease. Every animal which has no eyes or in which the eyes have been destroyed sees nothing. And although in the last analysis the different senses derive their source from touch, which is only variously modified in each of them, every animal which lacks nerves, the special organ of feeling, will not be able to experience any sort of sensation. For it does not have the intimate sense of its existence, it does not have the chamber to which sensation

must be conveyed, and consequently it would not be able to feel.

Thus, the sense of touch, the basis of the other senses, which is spread out into almost all parts of the bodies of those animals with nerves, does not exist any more in those which, like the polyps, lack nerves. In the latter, the parts are only simply irritable, and are so to a very high degree. But they have no feeling, and as a result, no type of sensation. In fact, in order for a sensation to take place, there must first be an organ to receive it (nerves) and then there must be some chamber or other (a brain or a longitudinal marrow with ganglia) where this sensation can be carried.

A sensation is always the consequence of a received impression which is carried immediately to an interior chamber where this sensation is formed. If you interrupt the communication between the organ which receives the impression and the chamber where the sensation is formed, all feeling immediately ceases in this place. One will never be able to contradict this principle.

No polyp can really be oviparous. For no polyp has a special organ for reproduction. Besides, to prepare real eggs, it is not only necessary that the animal has an ovary, but in addition it must have (or another individual of its species must have) a special organ for fertilization, and no one can demonstrate that the polyps are furnished with such organs. By contrast, we understand very well the buds which several of them develop for reproducing themselves. By paying a little attention to them, we perceive that these buds themselves are only fissions more isolated from the body of the animal, fissions less simple than those which nature uses

to multiply the animalcules which make up the last class of the animal kingdom.

The polyps are very irritable, move only with external stimulations foreign to them. All their movements are the necessary results of impressions received, and are generally carried out without acts of free will, because they do not know how to produce them, since they cannot have free will.

The light forces them constantly and always in the same manner to direct themselves its way, as it does with respect to branches and leaves or the flowers of plants, although more slowly. No polyp moves after its prey or seeks for it with its tentacles. But when some foreign body touches these same tentacles, they seize it, take it into the mouth, and the polyp swallows it without making any distinction about its appropriate nature or about its utility. It digests it and feeds on it, if this body is capable of being digested. It rejects it entirely, if it is preserved intact for some time in the alimentary canal. Finally it returns any remains which it cannot break down any more. But in all that, the action is a necessary one, without ever the possibility of a choice which permits the action to vary.

As to the distinction between the polyps and the radiates, it is very large and marked. We do not find in the interior of the polyps any distinct part having a radiating arrangement. Their tentacles alone have this arrangement, that is to say, the same as the arrangement of the arms of the cephalid mollusks, which we will surely not mix up with the radiates. Moreover, the polyps have a terminal superior mouth, while the mouth of the radiates is arranged differently.

It is not at all convenient to call polyps zoophytes, which is to say, animal-plants, because they are uniquely and completely animals, in that they have faculties generally not found in plants, that of being truly irritable and, generally, that of digesting. Finally their essential nature does not tend toward that of plants.

The only interrelationships between polyps and plants are as follows: (1) the rather similar simplification in their organic structure, (2) the faculty which many polyps possess of adhering to one another, to communicating together by their alimentary canal, and to form composite animals, (3) finally, the exterior shape of the masses which these combined polyps form. This shape for a long time made people take these masses for real plants, because often they are branched out in almost the same way.

Whether the polyps have a single or several mouths, it is always the case, with respect to them, that they lead to a single alimentary canal and, consequently, to one digestive organ, which all the plants lack.

If the degradation in the organic structure which we have noticed in all the classes from the mammals on is anywhere evident, it is surely among the polyps, whose organic structure is reduced to an extreme simplicity.

INFUSORIANSInfinitely small animals, with gelatinous transparent

bodies, homogenous and very contractile; having no specially distinct interior organ, but often with oviform gemmules, and displaying on the outside no radiating tentacles nor rotary organs.

Finally, we have arrived here at the last class in the animal kingdom, the one which makes up the most imperfect animals in all respects, that is, those whose organic structure is the simplest, who possess the fewest faculties, and who all seem, in truth, to be only sketches of animal nature.

Up to the present, I have combined these small animals in the class of polyps, of which they make up the last order under the name amorphous polyps, having no constant shape which is unique to all. But I recognized the necessity of separating them to create a special class. This does nothing to change the rank which I had assigned to them. All that results from this change is limited to a line of separation which the greatest simplification in their organic structure and their lack of radiating tentacles and rotary organs seem to require.

Since the organic structure of infusorians becomes increasingly simple, according to the genera which make up the class, the last of these genera present to us, in some way, the limit of animal nature. At least, the animals display the limit which we can reach. Particularly in the animals of the second order of this class, it is certain that all traces of the intestinal canal and mouth have disappeared entirely, that there are no organs at all, in a word, that they no longer carry out digestion.

The infusorians are only very small gelatinous bodies, transparent, contractile and homogenous, made up of cell tissue almost without any consistency, yet nevertheless irritable at all points. These small bodies, which appear only animated or moving points, nourish themselves by absorption and a constant water intake. Undoubtedly they are animated through the influence of subtle ambient fluids, like heat and

electricity, which simulate in them the movements which make up their lives.

In considering such animals, if we were still to assume that they possessed all the organs which we know about in other animals but that these organs are based in all the points of their bodies, how vain would such an assumption be!

In fact, the extremely weak (almost nonexistent) consistency of the parts of these small gelatinous bodies indicates that such organs must not exist, because it would be impossible for them to carry out their functions. It is clear enough that, in order for any organs to have the power to react upon fluids and to exert their appropriate functions, their parts must have the consistency and the tenacity which can give them force; now, this is precisely what cannot be assumed in connection with the frail animals under discussion.

Only among the animals of this class does nature appear to create spontaneous or direct generations, which she renews continually whenever circumstances are favorable for that. We will try to show that by spontaneous generations nature has acquired a way to create indirectly, after the passage of an enormous time, all the other races of animals which we know about.

What justifies our thinking that the infusorians or the majority of these animals owe their existence purely to spontaneous generations is that these frail animals all perish in the low temperatures brought on by the bad weather seasons. For surely we will not assume that such delicate bodies can leave any bud with sufficient consistency to preserve itself and to reproduce in warm seasons.

We find the infusorians in stagnant waters, in the infusions of plant or animal substances, and even in the reproductive liquid of the most improved animals. We find them exactly alike in all parts of the world, but only under circumstances where they could be created.

Thus, by considering successively the different systems of organic structures in animals, from the most complex right to the simplest, we have witnessed the degradation in that structure start in the very class which includes the most improved animals, then later progressively advance from class to class, although with anomalies produced by various sorts of circumstances, and finally, end in the infusorians. These last are the most imperfect animals, the simplest in organic structure, and those in which the degradation which we have followed has reached its limit, by reducing the animal's organic structure so that it consists of a simple body, homogenous, gelatinous, almost without consistency, without special organs, and uniquely formed from a very delicate cellular tissue, hardly sketched out, which appears to be brought to life by subtle ambient fluids which penetrate it and move out again constantly.

We have seen the successive process by which each particular organ, even the most essential, gets degraded little by little and finally goes away and disappears entirely long before reaching the other end of the order which we are following. And we have noticed that it is principally in the invertebrate animals that we see particular organs done away with.

To be sure, even before leaving the vertebrate division, we already perceive great changes in the improved condition

of the organs, and some of them, like the urinary bladder, diaphragm, vocal organ, eyelids, and so on, even disappear totally. In fact, the lung, the most improved organ for respiration, begins to be degraded in the reptiles and ceases to exist in the fish, never to reappear in any invertebrate animal.

Finally, the skeleton, the basis for the four extremities or limbs which the majority of vertebrate animals possess, begins to deteriorate, mainly in the reptiles, and is completely finished in the fish.

But it is in the division of invertebrate animals that we see the disappearance of the heart, brain, gills, conglomerate glands, the vessels appropriate for circulation, the organs for hearing, sight, sexual generation and even of feeling, as well as those for movement.

As I have already stated, it would be vain for us to seek out in a polyp, for example in a hydra, or in the majority of animals of this class, the least vestiges of nerves (organs of feeling) or muscles (organs of movement). Only irritability, with which every polyp is very clearly endowed replaces in it both the faculty of feeling which it cannot possess (because it does have any organ essential for that) and the faculty of voluntary movement (because all voluntary action is an act of the organ of intelligence and this animal totally lacks any organ like that). All its movements are the necessary results of impressions received in its irritable parts, exterior stimuli, and are carried out without any possibility of choice.

Put a hydra in a glass of water and place this glass in a room which does not receive light except through a window (hence, from a single side). When the hydra is established on a point of the sides of the glass, turn the glass in such a

manner that the daylight strikes another point opposite to the one where the animal is located. You will always see the hydra go in a slow movement to take up a position in the place where the light strikes and stay there for as long as you do not change the point. In doing this, the hydra follows what we see in the parts of plants which arrange themselves, without any act of will power, towards the quarter from which light comes.

Undoubtedly, wherever a particular organ no longer exists, the faculty which it gives rise to also ceases to exist. But, in addition, we see clearly that to the extent that an organ deteriorates and gets smaller, the faculty deriving from it becomes proportionally more obscure and imperfect. Thus, as we descend from the most complex toward the simplest animals, the insects are the last animals in which one finds eyes. But we have every reason to believe that they see very obscurely and make little use of their sight.

Thus, in moving through the animal chain from the most perfect to the most imperfect and by considering successively the different systems of organic structure which we distinguish in the extent of this chain, we see that the degradation in organic structure and of each organ (right to their total disappearance) is a reliable fact whose reality we have just confirmed.

This degradation is manifested even in the nature and consistency of the essential fluids and the flesh of animals. For the flesh and blood of mammals and birds are the most complex and vital materials that one can obtain from animals' soft parts. In addition, after the fish these materials progressively deteriorate to the point where in the soft

radiates, polyps, and above all in the infusorians, the essential fluid has nothing any more except the consistency and colour of water, and the flesh of these animals displays only a gelatinous material, hardly animalised. The soup which one might make out of such flesh would undoubtedly prove scarcely nourishing and strengthening for the person to tried it out.

Whether one acknowledges or not these interesting truths, nonetheless, those who observe facts carefully, overcome the widespread general prejudices, consult natural phenomena, and study nature's laws and constant march will always be led to them.

Now we are going to move on to consider something else, and we will try to prove that the environmental circumstances exercise a large influence on the actions of animals and that, as a result of this influence, the increased and sustained use of an organ or its lack of use are causes modifying the organic structure and shape of animals and giving rise to the anomalies which we observe in the structural progress within animal organization.

Chapter SevenConcerning the Influence of Circumstances on the Actions and Habits of Animals, and the Influence of the Actions and Habits of these Living Bodies As Causes Which Modify Their Organic Structure and Their Parts

What we are now concerned with is not a rational speculation but the examination of a reliable fact, a more universal one than people think and something to which we have neglected to pay the attention it deserves. Undoubtedly this is the case because on most occasions it is very difficult to recognize. This fact consists of the influence which circumstances exert on the different living things subject to them.

In truth, for quite a long time now we have noticed the influence of the different states of our organic structure on our characteristics, inclinations, actions, and even our ideas. But it seems to me that no one has get made known the influence of our actions and habits on our own organic structure. Now, as these actions and habits are entirely dependent on the circumstances in which we usually find ourselves, I am going to try to show how great the influence is which these circumstances exert on the general form, the condition of the parts, and even on the organic structure of living things. Thus, this chapter is going to explore this very well established fact.

If we had not had numerous occasions to recognize quite clearly the effects of this influence on certain living bodies which we have transported into entirely new

environments, very different from the ones where they used to live, and if we had not seen these effects and the changes resulting from them come to light in some way under our very eyes, the important fact under discussion would have always remained unknown to us.

The influence of circumstances is truly working always and everywhere on living bodies. But what makes this influence difficult for us to perceive is that its effects become perceptible or recognizable (especially in animals) only after a long passage of time.

Before laying out and examining the proofs for this noteworthy fact (something extremely important for Zoological Philosophy), let us summarize the thread of the ideas with which we started our analysis.

In the preceding paragraphs, we have seen that it is now an incontestable fact that, when we consider the animal scale in a sense opposite to the natural direction, we find that in the groups which form this scale there exists a sustained but irregular degradation in the organic structure of animals making up the groups, an increasing simplicity in the organization of living bodies and finally a corresponding diminution in the number of faculties in these beings.

This well known fact can provide us the greatest insights into the very order which nature followed in the production of all animals which she has brought into existence. But it does not show us why animals' organic structure, with its increasing complexity from the most imperfect right to the most improved, only displays an irregular gradation in which the range manifests a number of

anomalies or gaps which have no apparent order amid their variety.

Now, in seeking out the reason for this peculiar irregularity in the growing complexity of animals' organic structure, if we consider the results of the influences which the infinitely various circumstances in all the regions of the earth exert on the general shape, parts, and even the organic structure of these animals, then everything will be clearly explained.

In fact, it will be quite clear that the condition in which we see every animal is, on the one hand, the product of the increasing complexity in organic structure which tends to create a regular gradation and, on the other hand, the product of influences of a multitude of very different circumstances which continuously tend to work against the regularity in the gradations of the growing complexity in organization.

Here it becomes necessary that I explain what I mean by the following expression: Circumstances have an influence on the form and the organic structure of animals. What this means is that by undergoing significant change, the circumstances proportionally alter, over time, both the form and the organic structure itself

True, if someone takes these expressions literally, he would say I was making a mistake. For no matter what the circumstances can be, they do not work to bring about directly any modification whatsoever in the shape and organic structure in animals.

But significant changes in the circumstances lead, for animals, to great changes in their needs. Such changes in the needs necessarily lead to changes in their actions. Now, if the

new needs become constant or last a long time, the animals then acquire new habits which are just as long lasting as the needs which brought them about. That is what is easy to demonstrate and, indeed, requires no detailed explanation to be understood.

Thus, it is clear that a significant change in circumstances, once it becomes constant for a race of animals, leads these animals to new habits.

Now, if new circumstances have become permanent for a race of animals and have given these animals new habits, that is, have driven them to new actions which have become customary, that will result in the preferential use of one part over another and, in some cases, in the total disuse of some part which has become useless.

None of this should be considered a hypothetical or odd opinion. It is, by contrast, a truth which requires, to make it perfectly clear, nothing but attentive observation of facts.

We will see shortly through references to known facts which attest to these matters, on the one hand, that once new needs make some part essential, they effectively, by a sequence of efforts, give rise to that part; later its sustained use gradually strengthens and develops it, and finally finishes up by increasing its size considerably. On the other hand, we shall see that in some cases, the new circumstances and needs made some part totally useless. The total lack of use of this part brought it about that it gradually ceased undergoing the development experienced by the other parts. Thus, it grew smaller and weaker gradually, and finally, when this lack of use had been complete for a long time, the part in question

ended up disappearing. All that is reliable fact. I propose to give the most convincing proofs of this point.

In the plants where there are no actions and consequently, strictly speaking, no habits, significant changes in circumstances nonetheless lead to significant differences in the development of their parts. As a result, these different circumstances give rise to and develop certain parts, while they weaken several other parts and lead to their disappearance. But here everything exerts its effect through changes undergone in what the plant uses for nourishment, in what it absorbs and breathes, in the quality of heat, light, air, and humidity which the plant customarily then receives, and, finally, through the superiority which some of these various vital movements can gain over others.

Among individuals of the same species, if some are continually well nourished in circumstances favourable to their total development, while others find themselves in opposite circumstances, then there is produced a difference between the conditions of these individuals which gradually becomes very noticeable. How many examples I could cite concerning animals and plants which confirm the basis for this idea! Now, if circumstances remain the same, making the condition of the poorly nourished individuals habitual and constant, with suffering and malnourishment, their interior organic structure is finally changed. Reproduction among the individuals in question preserves the acquired modifications and ends up by giving rise to a race very different from the one made up of individuals who find themselves constantly in circumstances favourable to their development.

A very dry spring causes prairie grasses to grow very little, to remain thin and scrawny, to flower and bear fruit, although they have grown very little.

A spring mixed with hot days and rainy days brings about in these same grasses a generous growth, and the harvest of hay is then excellent.

But if with these plants some causes perpetuate unfavourable circumstances, they will vary proportionally, at first in their bearing or their general condition, and later in several specific characteristics.

For example, if a grain of some prairie grass or other is carried into a high place, onto a dry, arid, and rocky patch of land very exposed to the wind and can germinate there, the plant which can live in this place will always find itself malnourished, and if the individuals which it produces continue to exist in these poor circumstances, there will result a race truly different from the one which lives in the prairie (which is, however, the origin of the second race). The individuals of this new race will be small, scrawny in their parts, and some of their organs, having undergone more development than others, will then manifest strange proportions.

Those who have observed a great deal and consulted large collections have been convinced that as the conditions in the environment, exposure, climate, nourishment, way of life, and so on undergo changes, the characteristics of height, shape, proportions among the parts, colour, consistency, agility, and industry (for the animals) correspondingly change.

What nature does with a great deal of time, we do every day, when on our own we suddenly change the conditions in which a living plant and all the individuals of its species are found.

All botanists know that the plants which they take from the place where they were born to the gardens where they are cultivated undergo there gradual changes which end up making them unrecognizable. Many naturally very hairy plants in this way become smooth, or almost so; a number of those which were low and trailing straighten up their stem; others lose their thorns or protrusions; still others in our climate change from the woody and perennial stem conditions which they had in the hot climates where they used to be, to a herbaceous state, and among them several are nothing more than annuals. Finally, in our gardens the dimensions of these plants' parts themselves undergo very significant changes. The effects of these changed circumstances are so well recognized that botanists do not like to describe their garden plants until they are no longer recent cultivations.

Is not cultivated wheat (triticum sativum) a plant brought by man to the condition in which we see it today? Can anyone tell me in what country a similar plant lives naturally, that is, without being the result of its cultivation in some place near by?

Where do we find in nature our cabbage, lettuce, and so on, in the state where we produce them in our vegetable gardens? Is the case not the same with respect to the number of animals which domestication has changed or considerably modified?

How many different races of chickens and domestic pigeons we have acquired by raising them in different circumstances and different countries! How futile it is now to seek to find such animals in nature!

Those which are the least changed (undoubtedly because their domestication is more recent and because they do not live in a climate foreign to them) in some of their parts display differences no less significant through the habits which we have made them acquire. Thus our domestic ducks and geese find their type again in wild ducks and geese, but ours have lost the ability to rise up into the high regions of the sky and to fly across large territories. Finally a real change has occurred in their parts in comparison with the parts of the animals of the race from which they originated.

Who is not familiar with the fact that when some bird from our climate raised in a cage and living there five or six consecutive years is after that returned to nature, that is, given back its liberty, it is then no longer in a condition to fly like those similar to it which have always been at liberty? The slight change of circumstances working on this individual has, in truth, only diminished its capacity for flying and, undoubtedly, has not brought about any alteration in the shape of its parts. But if many successive generations of individuals of the same race were held in captivity over a long period of time, there is no doubt that even the shape of the parts of these individuals would have gradually undergone noticeable changes. This would be all the more reasonable if, in place of keeping them in a simple captivity constantly maintained, this circumstance had been simultaneously accompanied by a change into a very different climate and if these individuals had grown accustomed, by

degrees, to other forms of nourishment and to other actions for obtaining it. It is certain that these combined circumstances, once they become constant, would then create imperceptibly a new and totally special race.

Where do we see now in nature the many races of dogs which, as a result of the domesticity to which we have reduced these animals, we have brought into existence in the form they are today? Where do we find these mastiffs, greyhounds, water spaniels, spaniels, lap dogs, and so on and so on, races which display among themselves greater differences than those which we acknowledge as specific differences among animals of the same genus living freely in nature?

Undoubtedly, some first unique race, at the time very close to the wolf (if that is not in itself the true type), was domesticated by man at some epoch or other. This race, which did not then manifest any differences among its individuals, was gradually dispersed with human beings into different countries and climates. After some length of time, these same individuals experienced the influences of their surroundings and of their various habits which they had been made to acquire in each territory, underwent some remarkable changes, and formed different special races. Now, human beings, who, for trade or for some other sort of interest, move over very considerable distances, carried different races of dogs formed in countries far away into densely inhabited places, like great capital cities. At that time the crossbreeding of these races through reproduction thus gave rise successively to all those which we know about nowadays.

The following fact proves (with respect to plants) how much a change in some important circumstance has an influence on changing the parts of living organisms.

Whenever the plant ranunculus aquatis is immersed in water, its leaves are all markedly serrated and finely divided. But when the stem of this plant reaches the surface of the water, the leaves which develop in the air are enlarged, round, and simply lobed. If some feet of this plant succeed in pushing into a soil which is only humid, without being underwater, their stems then are short and none of their leaves is divided up into tiny sections. This example gives rise to the plant ranunculus hedereaceus, which botanists, when they encounter it, consider a species.

There is no doubt that, so far as animals are concerned, important changes in the circumstances where they usually live produce similar changes in their parts. But here the changes are much slower manifesting themselves than in the plants. Consequently, they are less perceptible to us and their cause less recognizable.

As for the circumstances which have the most power to change the organs in living bodies, the most influential is undoubtedly the diversity in the locations where the animals live. But, in addition, there are many others which later have a considerable influence in producing the effects we are discussing.

We know that different places have a different nature and quality, on account of their positions, compositions, and climates. That is easy to notice as we go through different places differentiated by specific qualities. Here is one cause of variation in the animals and plants which live in these

different places. But what we do not understand sufficient well and what people even generally refuse to believe is that each place itself changes, over time, in exposure, climate, nature, and quality, although so slowly in comparison with our extents of time that we attribute to that place a perfect stability.

Now, in both cases, these altered locations change correspondingly the circumstances relevant to living things who live there. And these circumstances then produce other influences on these living things themselves.

From that we perceive that if there are extremes in such changes, there are also slight modifications, that is to say, intermediate degrees which fill up the gap between the extremes. Consequently, there are also modulations in the differences which distinguish what we call species.

Thus, it is evident that all the surface of the earth displays in the nature and the situation of the materials which make up its different points a diversity of circumstances which throughout is allied to the diversity in the forms and the parts of animals, independent of the special diversity which results necessarily from the progress in the complexity of organic structure in each animal.

Everywhere where animals can live, the circumstances which create there an order of things remain the same for a long time and do not really change except with such an excessive slowness that man is not capable of perceiving it directly. He is obliged to consult the monuments to recognize that in each of these places the order in things which he finds there has not always been the same and to sense that it will change once again.

The races of animals living in each of these places must thus preserve their habits for quite a long time; hence the apparent permanence to us of what we call species, a permanence which has given rise in us to the idea that these races are as old as nature.

But in the different habitable locations on the surface of the earth, the nature and situation of territories and climates there constitute for animals, as for plants, circumstances different to all sorts of degrees. The animals inhabiting these different places must therefore be different from each other not only because of the state of complexity in the organic structure of each race but also because of the habits which the individuals of each race have been forced to acquire there. Moreover, as the naturalist traversing parts of the earth's surface sees conditions change in a slightly perceptible way, he always then sees the characteristics of species changing proportionately.

Now, the true order of things relevant to consider in all this consists in recognizing the following:

1. All slightly remarkable changes later maintained in circumstances where each race of animals is located works to create in that race a real change in its needs. 2. All changes in animals' needs require of them alternative actions to satisfy the new needs and, consequently, alternative habits. 3. Since the satisfaction of every new need demands new actions, it requires from the animal experiencing that need either the more frequent use of some of its parts which previously it used less often (something which develops and makes that part grow), or the use

of new parts which the needs imperceptibly bring forth in the animal by the efforts of its interior feeling. This I will establish very soon by known facts. Thus, to reach an understanding of the true causes of so

many diverse forms and so many different habits, examples of which the known animals manifest to us, we must take into account the fact that the infinitely diversified and slowly changing conditions in which the animals of each race are successively located have led, in each of them, to new needs and necessarily to changes in their habits. Now, once this truth, which one cannot contest, is recognized, it will be easy to see how animals have been able to satisfy the new needs and to acquire new habits, if we give some attention to the two following laws of nature, which observation has always confirmed.

First LawIn every animal which has not exceeded the limit of its

development, the more frequent and sustained use of any organ gradually strengthens this organ, develops it, makes it larger, and gives it a power proportional to the duration of this use; whereas, the constant lack of use of such an organ imperceptibly weakens it, makes it deteriorate, progressively diminishes it faculties, and ends by making it disappear.

Second LawEverything which nature has made individuals acquire

or lose through the influence of conditions to which their race has been exposed for a long time and, consequently, through the influence of the predominant use of some organ or by the influence of the constant disuse of this organ, nature preserves by reproduction in the new individuals arising from

them, provided that the acquired changes are common to the two sexes or to those who have produced these new individuals.

These are the two constant truths which cannot be overlooked except by those who have never observed nor followed nature in her work or by those who have let themselves be led into the error which I am going to contest.

Once naturalists noticed that the forms of animals' parts are always linked to the use of these parts, they thought that the forms and the condition of the parts had led to the usage. Now, there is the mistake. For it is easy to demonstrate through observation that, by contrast, it is the needs and the use of the parts which have developed them, factors which even produced the parts at a time when they did not exist and which, consequently, gave rise to the condition in which we see them in each animal.

In order for that not to be the case, it would have been necessary for nature to create for the animal parts as many forms as required by the diversity of circumstances in which they have to live and that these forms, as well as the circumstances, never change.

That is certainly not the natural order which exists. If it had ever really been like that, we would not have race horses in the form of those in England; we would not have our large draught horses, so heavy and different from these race horses, for nature on her own did not produce anything like them. For the same reason we would not have basset hounds with crooked limbs, such swift-running greyhounds, water spaniels, and so on. We would not have tailless hens, fantail pigeons, and so on. Finally, we would be able to cultivate

wild plants as much as we liked in the rich fertile soil of our gardens, without fear of seeing them change through long cultivation.

In this matter, for a long time we have had a feeling for what is really the case, because we developed the following sentence, which has become proverbial and universally known: habits form a second nature.

To be sure, if habits and the nature of every animal were incapable of ever changing, the proverb would be false, would not have arisen, and would not have been able to be preserved in the event someone had proposed it.

If one considers seriously everything which I have just revealed, one will sense that I grounded my views rationally when in my work entitled Research Into Living Bodies (p. 50), I laid down the following proposition:

"It is not the organs, that is, the nature and the form of the animal's body parts, which have given rise to its habits and special faculties, but, by contrast, its habits, manner of life, and circumstances of the individuals from which the animal comes to possess, over time, the form of its body, the number and condition of its organs, and finally the faculties which it enjoys." Let people consider well this proposition and bring to it

all the observations which nature and the state of things enable us to make all the time. Then its importance and reliability will become for us the most significant evidence.

Favourable times and circumstances are, as I have already said, the two main means employed by nature to bring into existence all her productions. We know that time

has no limits for her and that, as a result, she always has time to spare.

As to the circumstances which she needed and which she still uses every day to vary everything which she continues to produce, we can say that circumstances are, in some way, for her inexhaustible.

The main circumstances arise from the influence of climates, various temperatures in the atmosphere and all the environmental surroundings, the variety of places and their exposure, habits, the most ordinary movements, the most frequent actions, finally the means of self-preservation, reproduction, and so on.

Now, as a result of these various influences, the faculties expand and grow stronger through use. With new habits preserved over a long time they diversify. Imperceptibly the arrangement, consistency, in a word, the nature and the condition of the parts, as well as the organs, undergo the consequences of all these influences, preserving and propagating themselves in reproduction.

These truths, which are only the consequences of the two natural laws set forth above, are, in every case, amply confirmed by the facts. They indicate clearly the march of nature in the variety of her productions.

But instead of contenting ourselves with generalities which we could consider hypothetical, let us examine the facts directly. Let us consider in animals what is produced by the use or lack of use of their organs on these very organs, according to the habits which each race has been compelled to acquire.

Now, I am going to prove that the constant lack of exercise with respect to an organ at first reduces its faculties, then gradually shrinks it, and ends up by making it disappear or even destroying it, if this lack of use continues for a long time in a sequence of successive generations of animals of the same race.

Then I will reveal how, by contrast, the habit of exercising an organ, in every animal which has not reached the limit in the diminution of its faculties, not only improves this organ's faculties and makes it grow, but also makes it develop and acquire dimensions which imperceptibly change it, so that in time it makes it quite different from the same organ examined in another animal which exercises it much less.

The lack of use of an organ, once it has become constant because of the habits which one has taken up, gradually diminishes that organ and ends up by making it disappear and even destroying it.

Since such a claim cannot be accepted without demonstrations (and not by a simple declaration), let us try to set out evidence by citing the major known facts which constitute the basis for it.

The vertebrate animals, in all of whom the design of the organic structure is almost the same, although they manifest much diversity in their parts, have their jaws equipped with teeth. However, in those among them in which circumstances have developed the habit of swallowing the objects on which they feed without previously chewing them at all, we find that their teeth have not undergone any development. Thus, these teeth either have remained hidden

between the bony layers of the jaws, without being capable of appearing on the outside, or have even been destroyed right down to their basic elements.

In the whale, which we thought entirely without teeth, M. Geoffroy has found them hidden in the jaws of the fetus of the animal. This professor has also located in birds the groove where the teeth must have been placed. But we do not see them there any more.

Even in the class of mammals, which includes the most perfect animals, mainly those in which the design of the organic structure of vertebrates has been effected most completely, not only does the whale have no more teeth to use, but we also find there in the same class the ant eater (Myrmecophaga) in which the habit of not chewing has been introduced and preserved for a long time in the species.

Having eyes in the head is characteristic of a large number of various animals and is an essential part of the design in the organic structure of vertebrates.

Nevertheless, the mole which, through its habits, makes very little use of sight, has only very small eyes, hardly apparent, because the animal makes use of this organ very rarely.

The aspalax of Olivier (Voyage in Egypt and in Persia, II, pl. 28, f. 2), which lives underground, like the mole, and which probably exposes itself to the light of day even less than that animal, has completely lost the use of sight. Moreover, it manifests no more than vestiges of the organ which is the seat of sight. In addition, these vestiges are completely hidden under the skin and under some other parts

which cover them over and do not provide any more the least access to light.

The Proteus, an aquatic reptile related (by its affinities) to the salamanders and living in deep and dark cavities under the water, like the aspalax, has only vestiges of the organs of sight, vestiges which are covered and hidden in the same manner.

Here is a decisive consideration concerning the question which I am at present raising.

Light does not penetrate everywhere. Consequently, animals who habitually live in the the places where there is no light lack the opportunity to exercise the organ of sight, if nature has furnished them with one. Now, the animals which are part of a structural design in which the eyes are necessarily a part must have had them in their origins. However, since we find among these animals ones which are without the use of this organ and which have only hidden and covered vestiges of it, it becomes evident that the diminution and even the disappearance of the organ in question are the results, for this organ, of a constant lack of exercise.

What proves the point is the fact that the organ of the ear is never like this. We always find it in those animals in which the nature of their organic structure requires that the ear be present. Here is the reason.

The material of sound8, which is set in motion by the shock or the vibration of bodies, transfers to the organ of

8Physicists think and even state that atmospheric air is the unique medium for sound, that is to say, that it is the air which, set in motion by the shocks or the vibrations of bodies, transmits to the organ of the ear the impressions of the oscillations which it has received.

hearing the impression which it has received, penetrates everywhere, and moves through every medium, even the masses of the densest bodies. The result is that every animal which is part of an organic structural design in which the ear is an essential part always has the opportunity to exercise this organ in whatever place it dwells. Thus, among the vertebrate animals we do not witness any which lack the organ of the ear, and after that point, when this same organ is lacking, we do not find it again later in any of the animals of the later classes.

That this view is an error is confirmed by a number of known facts which prove that it is impossible for air to penetrate to all regions where the material producing sound actually does penetrate.

See my Memorandum on the substance of sound, printed at the end of my Hydrogeology, p. 225, in which I have set forth the proofs of this mistake.

Since the publication of my memorandum (which people have been reluctant to refer to) great efforts have been made to reconcile the known velocity for the propagation of sound in air with the sluggishness of the air particles which makes the propagation of these oscillations too slow to equal this speed. Now, since the air in its oscillations necessarily undergoes successive compression and dilation in parts of its mass, people have used the products of the calories given off in the sudden compression of air and of those absorbed in the rarefaction of this fluid. Thus, by using the results of these products and their size, as determined by appropriate hypotheses, geometricians now provide a rational basis for the speed with which sound propagates itself in air. But that does not square at all with facts which confirm that sound propagates itself through bodies which air is incapable of moving through or of setting any of its parts in motion.

In fact, the assumption concerning the vibration of the smallest parts of solid bodies is a very doubtful oscillation which cannot propagate itself except in homogeneous bodies with the same density and cannot extend from a dense body into a rarefied body, nor from the latter into another very dense body. This assumption cannot be reconciled with the well known fact about the propagation of sound through heterogeneous bodies with different densities and very different natures.

Such is not the case with the organ of sight, for we see this organ disappear, reappear, and disappear once more, as a result of the possibility or the impossibility of the animal's making use of it.

In the acephalid mollusks, the great development of the mantle has made their eyes and even their head entirely useless. Although these organs are part of a structural plan which should include them, they have therefore had to disappear and die out through a constant lack of use.

Finally, part of the organic structural design of reptiles, as in other vertebrate animals, includes having four limbs dependent on their skeleton. Consequently, snakes should have four of them, especially since they do not make up the last order of reptiles and since they are more distant from the fish than are the batrachians (frogs, salamanders, and so on).

However, snakes took up the habit of crawling on the ground and hiding in the grass. Thus, their body, as a result of constant and repeated efforts to extend itself, so as to pass into narrow spaces, acquired a considerable length, totally disproportionate to its size. Now, limbs would have been really useless to these animals and consequently remained unused (for extended limbs would have been an impediment to their need to crawl, and very short limbs, necessarily four in number, would have been incapable of moving their bodies). Thus the lack of use of these parts, remaining constant for the races of this animal, made these very parts disappear entirely, although the limbs were actually in the design of the organic structure of animals of their class.

Many insects which, according to the natural characteristics of their order and even their genus, should

have wings, lack them more less completely, because they do not use them. A number of coleoptera, orthopetera, hymenoptera, and hemiptera, and so on give us examples of this fact. The habits of these animals never put them in situations where they used their wings.

But it is not sufficient to provide an explanation for the cause which has led to the state of the organs of different animals, a condition which we observe is always the same in those of the same species. In addition, it is necessary to make known the alterations brought about in the organs of a single individual during its lifetime,. solely as the product of a great mutation in the habits unique to the individuals of its species. The following extremely remarkable fact will complete the proof of the influence of habits on the condition of the organs and establish how much sustained changes in the habits of an individual lead to changes in the condition of the organs which are brought into action during the exercise of these habits.

Mr. Tenon, member of the Institute, has made known to the Class of Sciences, that he examined the intestinal canal of several men who had been passionate drinkers for a large part of their lives. He constantly found the organ shortened by an extraordinary amount in comparison with the same organ in all those who had not picked up the same habit.

We know that great drinkers, or those who have been addicted to drinking, eat very little solid food, that they eat almost nothing, and that the drink which they consume in abundance and frequently is sufficient to nourish them.

Now, since the alimentary fluids, especially spirit drinks, do not stay for long either in the stomach or in the

intestine, among drinkers the stomach and the rest of the intestinal canal lose the habit of being distended, just as the stomachs of sedentary persons constantly busy with intellectual work who are accustomed to eating only a little gradually over time contract, and their intestines grow shorter.

This matter is not at all a question of a shrinking and a contraction brought about by a gathering in of the parts which would allow for an ordinary extension if these internal organs were filled, rather than undergoing a sustained emptiness. It is rather a question of a real and considerable shrinkage and contraction such that these organs would break rather than yield suddenly to causes which demand an ordinary extension.

Compare, at entirely similar ages, a man who, in order to free himself for studies and habitual intellectual work, has acquired the habit of eating very little with another who habitually takes plenty of exercise, frequently goes out of his house, and eats well. The stomach of the first will have very little capacity and will be filled by a very small quantity of nourishment, while the stomach of the second will have preserved and even increased its capacity.

There we have an organ strongly modified in its dimensions and capacity by the single cause of a change in habits over the lifetime of an individual.

The frequent use of an organ, once it becomes constant and habitually, increases the capacities of this organ, develops it, and makes it acquire dimensions and an active power which the organ does not possess in the animals which exercise it less.

It has just been shown that the lack of use of an organ which ought to exist modifies it, diminishes it, and ends up destroying it.

Now I am going to establish that the continuous use of an organ, along with the efforts made to derive from it a substantial benefit in circumstances which demand it, fortifies the organ, extends and enlarges it, or makes new organs from it which can carry out functions which have become essential.

The bird drawn to water by the need to to find there prey which sustains its life extends the digits on its feet with which it wishes to strike the water and move on the surface. The skin which unites these digits at their base, because of these constantly repeated separations of the digits, acquires the habit of stretching itself. Thus, over time, the large membranes which link the digits of ducks, geese, and so on are formed just as we see them. The same efforts made for swimming, that is, to push the water in order to advance and move in this liquid have in the same manner extended the membranes between the digits of frogs, sea-tortoises, otter, beaver, and so on.

By contrast, the bird whose way of living accustoms it to perching in trees and which descends from individuals which have all acquired this habit, necessarily has longer digits on its feet shaped in a different way from those of the aquatic animals which I have just cited. Its claws, over time, grow longer, sharper, and hook-like to grasp the branches on which the animal rests so often.

In the same way, we see that the shore bird which has no inclination to swim but which nevertheless needs to approach the water's edge to find its prey constantly runs the

risk of sinking down in the mud. Now, this bird, wishing to act in such a way that its body does not sink in liquid, makes every effort to extend and lengthen its feet. From that it follows that the long habit which this bird and all those of its race acquire of extending and lengthening their feet brings it about that the individuals of this race find themselves elevated as if on stilts, having gradually developed long bare legs, that is, legs without feathers up to the thighs and often further than that. Système des Animaux sans vertèbres, p. 14.

We also know that the same bird, wishing to fish without getting its body wet, is required to make continual efforts to lengthen its neck. Now, the consequences of these habitual efforts in this individual and in those of its race must have, over time, lengthened their necks remarkably, a point which is, in fact, confirmed by the long neck of all shore birds.

If some swimming birds, like the swan and the goose, in which the legs are short, have nonetheless a very long neck, the reason is that these birds, while moving along on the water, are accustomed to plunge their heads down into it as deeply as they can to take from there the aquatic larvae and different animalcules on which they feed. They make no effort to lengthen their limbs.

If an animal, in order to satisfy its needs, makes repeated efforts to lengthen its tongue, that organ will acquire a considerable length (anteater, green woodpecker). If the animal needs to seize something with this same organ, then its tongue will divide and become forked. The tongue of the humming birds, who seize things with their tongue, and that of lizards and snakes, who use their tongues to feel and

recognize the bodies in front of them prove what I am proposing.

Needs, always induced by circumstances, and the later efforts maintained to satisfy those needs are not limited in the results of their modifications, that is, in increasing or diminishing the extent and the capacities of organs. But they also succeed in removing these same organs, when certain of these needs are not essential.

The fish which customarily swim in large bodies of water have a need to see laterally. They, in fact, have their eyes placed on the sides of their heads. Their bodies, more or less flattened, depending on the species, have their edges perpendicular to the plane of the water, and their eyes are placed in such away that there is one eye on each flat side. But those fish whose habits require them constantly to come close to the shore, particularly to shores slightly inclined or with a gentle slope, have been forced to swim on their flattened side, in order to be able to approach more closely the edges of the water. In this situation, receiving more light from above than below and having a special need to be always attentive to what is found above them, their need has induced one of their eyes to undergo a sort of displacement and to occupy the very remarkable position that we know about in soles, turbots, dabs, and so on (the Pleuronectes and Achirus). The location of these eyes is no longer symmetrical, because it results from an incomplete mutation. Now, this mutation is completely realized in the skates, where the transverse flattening of the body is totally horizontal, as well as the head. Thus, the eyes of rays, both placed on the upper surface, have become symmetrical again.

The snakes, which crawl on the surface of the earth, need mainly to see elevated objects which are above them. This need must have influenced the placement of the organ of sight in these animals. In fact, they have their eyes situated in the lateral and upper part of the head, in such a way that they can easily perceive what is above them or beside them. But they hardly see at all what is in front of them a very short distance away. However, forced to make up for this defect of vision for understanding the bodies which are in front of their heads and which might injure them if they moved forward, they were not able to perceive these bodies except with their tongue, which they were obligated to extend with all their force. This habit not only helped to make this tongue thin, very long, and contractile, but also it has also forced the tongue to divide itself in the majority of species in order to feel several objects at once. It even permitted them to form an opening on the edge of their muzzle, so that they could move the tongue through it without separating their jaws.

Nothing is more noteworthy than what is produced by the habits of the herbivorous mammals.

The quadrupeds in which circumstances and the needs created by these over a long period of time have developed (in it as well as in the individuals of the race) the custom of grazing on grass, moves only on the ground, and finds itself obliged to remain their on its four feet for most of its life, not generally carrying out much movement (or only moderate movement). The large amount of time this sort of animal is required to use each day to fill itself up with a single form of nourishment to which it is accustomed brings it about that it exercises itself very little by moving around and that it uses its limbs only to hold it up on the earth, to move or to run,

and it never makes use of its limbs to cling to and climb up trees.

From this habit of consuming, every day, huge volumes of material for nourishment, which distends the organs taking it in, and from the habit of only carrying out moderate movements the result is that the bodies of these animals have grown considerably thicker, have become heavy and huge, and have acquired a really large volume, as we see in elephants, rhinoceroses, oxen, buffaloes, horses, and so on.

The habit of staying upright on four feet for the greater part of the day in order to graze has given rise to a thick horn which envelops the digits of their feet. And since these digits have rested without being exercised by any movement and since they have not served any other purpose than to hold the animals up (just like the rest of the foot) most of these digits have shrunk, dwindled, and have finally disappeared. Thus, in the pachyderms, some have on their feet five digits enveloped in horn and, consequently, their hoof is divided into five parts; others have only four and still others have only three. But in the ruminants, which appear to be the oldest of the mammals limited to sustaining themselves only on land, there are no longer more than two digits on the feet, and in the solipeds there is only one (horses, donkeys).

However, among the herbivorous animals, and particularly among the ruminants, it happens that there are some which, due to circumstances in the desert countries which they inhabit, are ceaselessly in danger of being the prey of carnivorous animals and which can find safely only in sudden flight. Necessity has thus forced them to practice rapid running. From the habit which they have acquired from

that, their bodies have become more svelte and their limbs much more slender. We see examples of them in antelopes, gazelles, and so on

In our climate, other dangers continually expose the red deer, roe deer, and fallow deer to the mortal peril of hunting by human beings and reduce the animals to the same need, force upon them similar habits, and have given rise to the same productions with respect to them.

Ruminant animals can make use of their feet only to hold themselves up. Since they have little power in their jaws, which are exercised only by cutting and browsing on grass, they cannot fight each other except with blows of the head, aiming the crown of their heads against each other.

In their fits of anger (which are frequent, above all among the males), their inner feeling, in these efforts, very strongly direct the fluids towards this part of their heads and there create a secretion of horny material in some and in others a bony material mixed with horny material. This gives rise to solid protuberances. Hence, the origin of horns and antlers, with which the heads of the majority of these animals are armed.

In this matter of habits, it is remarkable to observe the result in the peculiar form and height of the giraffe (camelo-pardalis). We know that this animal, the largest of the mammals, lives in the interior of Africa and dwells in those places where the earth, almost always arid and without grass, requires the animal to browse on the foliage of trees and constantly to try hard to reach that foliage. As a result of this habit, maintained for a long time in all the individuals of its race, the animal's front limbs have become longer than those

at the back, and its neck has grown longer to such an extent that the giraffe, without rearing up on its hind legs, lifts its head and reaches up to six metres in height (close to twenty feet).

Among the birds, the ostriches, lacking the capacity to fly and elevated on very high limbs, probably owe their remarkable form to analogous circumstances.

The result of habits is just as noteworthy in the carnivorous mammals as it is in the herbivores. But it manifests effects of a different sort.

In fact, among these mammals those who are accustomed, along with their race, to climb, to scratch away in order to dig a hole in the ground, or to rip apart other animals which they attack and kill for prey have a need to use the digits on their feet. Now, this custom has favored the separation of their digits and has formed the claws with which we see them equipped.

But among the carnivores, there are those which are obliged to run in order to catch their prey. Now, among these animals those in which need (and consequently custom) has made it necessary every day for them to rip with their claws and to push them deep into the body of another animal in order to hang on to it and finally to make an effort to tear out the part they have seized must have, through repeated efforts, acquired for these claws a size and curved shape which would have then made them very awkward for walking or running on stony ground. In this case, what happened was that the animal was obliged to make other efforts to push back these excessively projecting curved claws which got in its way. From this gradually resulted the formation of these

remarkable sheaths in which cats, tigers, lions, and so on withdraw their claws when they are of no use.

Thus, efforts made in any direction whatever, if maintained for a long time or habitually made by certain parts of a living body to satisfy needs demanded by nature or circumstances enlarge these parts and make them acquire dimensions and a shape which they would never have attained if these efforts had not become the habitual action of the animals which carried them out. Observations undertaken on all the known animals provide examples of this everywhere.

Is it possible that there is a more striking one than the kangaroo? This animal, which carries its little ones in the pouch which it has under its abdomen, has acquired the habit of holding itself upright, balanced only on its back feet and its tail, and it does not move except with the help of a series of leaps in which it maintains its upright posture so as not to upset its young. From this come the following:

1. Its front limbs, of which it makes very little use and on which it leans only in the moment when it abandons its upright posture, have never undergone a development proportional to that of the other parts and have remained thin, very small, and almost without force.

2. The back limbs, almost constantly in action, whether to hold up all the body or to carry out its jumps, have, by contrast, undergone a considerable development and have become very large and very powerful.

3. Finally, the tail which we see here used a great deal to hold the animal up and for carrying out its principal

movements has acquired at its base an extremely remarkable thickness and power.

These well known facts are surely very relevant to show what results from the habitual use among animals of an organ or any part whatever. And if, when one observes in an animal, an organ noticeably developed, strong, and powerful, people maintain that habitual exercise has done nothing to bring that about, that its sustained lack of use would not take anything away, and that finally this organ has always been just as it is now ever since the creation of the species to which this animal belongs, I will enquire why our domestic ducks cannot fly any more like wild ducks. In a word, I will cite a multitude of examples directly relevant to us which point to the different results of the exercise or the lack of exercise of any of our organs, although these differences might not be maintained in individuals who come later through reproduction.

I will make known in the second part that, when will power determines that an animal carry out some action or other, the organs which must execute this action are immediately stimulated to it by the inflow of subtle fluids (the nervous fluids) which become there the determining cause of the movements which the action in question demands. A multitude of observations confirms this fact, which people cannot now doubt.

From this it follows that multiple repetitions of these actions of the organic structure strengthen, extend, develop, and even create organs essential for these actions. It is only necessary to observe attentively what happens everywhere in

this matter to become convinced of the basis for this cause of developments and organic alterations.

Now, every change acquired in an organ by a habitual use sufficient to have brought it about then preserves the change by reproduction, if it is common to individuals which, in the act of reproduction, come together for the propagation of their race. Finally, this change passes itself on and thus is transmitted to all the individuals which come after and which are subject to the same circumstances, without being obliged to acquire the change in the same way it was actually created.

Moreover, in the reproductive unions, the blending of individuals who have different qualities and forms is necessarily opposed to the constant propagation of these qualities and forms. In man, who is subjected to so many diverse influential circumstances, that is what prevents the accidental qualities or defects which he happens to acquire from preserving and propagating themselves by reproduction. If we have a case where two individuals with remarkable shapes or any defects always couple together, they will reproduce the same particular features, and if later generations limit themselves to similar unions, a particularly distinct race will then be formed from them. But constant interbreeding among individuals who do not have the same distinctive features will erase all distinctive particularities acquired by distinctive circumstances. Hence, we can be assured that if the distance between their dwelling places did not separate human beings, the reproductive mixing would do away with the general characteristics which distinguish the different nations.

If I wished here to review all the classes, all the orders, all the genera, and all the species of animals which exist, I could show that the structure of individuals and their parts, their organs, their capacities, and so on and so on, are everywhere uniquely the result of the circumstances which each race finds itself subjected to by nature and of the habits which the individuals making up a race have been obliged to acquire. I could show that these are not the result of a form existing in primitive times which has forced animals into those habits which we know about.

We know that the animal called the ai, or the sloth (bradypus tridactylus) is constantly in a feeble state, so much so that it carries out only very slow and very limited movements and that it moves on the ground with difficulty. Its movements are so slow that people allege that it can make only fifty paces in a single day. We also know that the organic structure of this animal is entirely linked to its feeble condition or its inability to move and that if it wished to make movements different from those which we have seen it carry out, it would not be able to.

Hence, by assuming that this animal had received from nature the organic structure which we know about, people said that this organization forced upon it the habits and the sorry condition in which it finds itself.

I am a long way from believing this. For I am convinced that the habits which individuals of the sloth family were forced to acquire originally must necessarily have led to its present condition.

If continual dangers had in earlier times brought it about that individuals of this species took refuge in the trees,

habitually lived there, and derived nourishment from their leaves, then it is clear that they would have had to forgo a multitude of movements which animals living on the ground are in a position to carry out. All the needs of the ai would thus have been reduced to hanging from branches, crawling or dragging themselves along there to catch leaves, and finally remaining in the tree in an inactive state so as to avoid falling down. Moreover, this style of inactivity would have been constantly fostered by the hot climate, because among warm-blooded animals heat encourages rest rather than movement.

Now, over a long period of time, the individuals of the sloth family would have continued the habit of remaining in the trees and not moving there other than slowly and with little variety, in a way which could meet their needs. Their organic structure gradually would have accorded itself to their new habits. From that, the following will result:

(1) the arms of these animals, by making constant efforts to hold readily onto the tree branches, would have grown longer;

(2) the nails on their digits would have acquired considerable length and a hooked shape, through the sustained efforts of the animal to hold onto its position;

(3) since their digits would never be exercised with remarkable movements, they would have lost all their mobility, grown together, and preserved only the ability to clench or unclench all together;

(4) since their thighs would continually wrap around the trunk or the large tree branches, they would have acquired a customary space between them, something which would help to enlarge the pelvis and to push the cotyloid cavities towards the back;

(5) finally, a large number of their bones would have fused together and several parts of their skeletons would have taken on an arrangement and a shape corresponding to the animals' habits, something different from what they would have to have for other habits.

There we have what people will never be able to doubt, because, in fact, nature, in a thousand different cases, always shows us analogous facts, in the power of circumstances on the habits and of habits on shapes, arrangements, and proportions of animals.

Since a greater number of references is quite unnecessary, here we have what the point of this discussion comes down to.

The fact is that the various animals all have, in accordance with their genus and their species, particular customs and always an organic structure which accords perfectly with these customs.

From a consideration of this fact, it seems that we are free to admit that either one or the other of the two following conclusions and that neither of them can be proven.

Conclusion Accepted Up Until Today: Nature (or its author), in creating the animals, anticipated all the possible

sorts of circumstances in which they would have to live and gave to each species a fixed organic structure, as well as a determined and invariable form for its parts, which forces each species to live in those places and climates where it is located and to maintain there the habits which we know it has.

My Personal Conclusion: Nature, by producing in succession all the animal species and beginning with the most imperfect or the simplest, gradually made the organic structure more complicated; as these animals generally spread out into all the habitable regions of the world, from the influence of the circumstances which each species encountered, it acquired the habits which we know in it and the modifications in its parts which observation reveals to us in that species.

The first of these conclusions is the one which people have drawn up to the present time, that is to say, that it has been just about universal. It assumes in each animal a constant organic structure and parts which have never varied and which will never vary; it further assumes that the circumstances in the places where each species of animals dwells never varies in these locations; for if they did vary, the same animals would no longer be alive and the possibility of finding other similar circumstances and of transporting themselves there would be forbidden to them.

The second conclusions is my own. It assumes that through the influence of circumstances on habits and later the influence of habits on the condition of the parts and even on the condition of the organic structure, each animal can undergo in its parts and organic structure modifications

capable of becoming really significant. This has given rise to the condition in which we find all the animals.

To establish that this second conclusion is groundless, it is first necessary to prove that each point on the surface of the earth never varies its nature, exposure, lofty or low elevation, its climate, and so on and so on, and, beyond that, to show that no part of animals undergoes, even with the passage of a great deal of time, any modification occasioned by a change in its circumstances and by the necessity which forces them to a style of life and action different from what is habitual to them.

Now, if a single fact confirms that an animal which has been domesticated for a long time differs from the wild species from which it originated and if, in such a domesticated species, we find a great structural differences between individuals which we have subjected to some habit and those whom we have forced into different habits, then it will be certain that the first conclusion does not conform at all to natural laws and that, by contrast, the second is perfectly in accordance with them.

Thus, everything comes together to establish my assertion, namely, that is is not the form (wether of the body or the parts) which gives rise to the habits and the manner of living in animals, but that, by contrast, it is the habits, the manner of life, and all the other influential circumstances which have, over time, shaped the form of the body and the parts of animals. With new shapes, new faculties were acquired, and gradually nature came to the point of creating the animals such as we see them now.

Could there be in natural history a more important conclusion, one to which we ought to give more attention, than the one with I have just revealed?

Let us conclude this first part with the principles and the exposition of the natural order of animals.

Chapter Eight

Concerning the natural order of animals and the structure we must give to their general distribution so that it

conforms to the very order of nature.

I have already remarked (Chapter V) that the essential aim of a distribution of animals must not limit itself, on our part, to the possession of a list of classes, genera, and species. This distribution must at the same time display, in its structure, the means most favorable to the study of nature, something which is most relevant to make us understand her progress, her means, and her laws.

However, I do not hesitate to point out that our general distributions of animals up to the present day have been given a structure which reverses the very order nature followed in giving rise successively to her living productions. Thus, in moving, according to custom, from the most complex towards the most simple, we make knowledge of the progress in the composition of organic structure more difficult to grasp, and we put ourselves in the position of perceiving less easily both the causes of this progress and the interruptions here and there in it.

When we realize that something is useful, even that it is indispensable for the goal we propose and that there is nothing inconvenient about it, we must hurry to make use of it, even though it is contrary to custom.

Such is the case concerning the structure which we must give to the general disposition of animals.

Moreover, we will see that it is not at all an indifferent matter to begin this general distribution of animals at either one of its extremities and that what should come at the start of the order cannot be simply a matter of our choice.

The custom which was introduced and which people have followed up to the present day of putting at the head of the animal kingdom the most perfect animals and to finish this kingdom by the least perfect and the simplest in organic structure owes its origin, in part, to the tendency which makes us always give precedence to the objects which we find striking, which please us, or which interest us the most, and, in part, to the fact that we have preferred to move from the best known towards the least known.

At the time when people began to occupy themselves with the study of natural history, these considerations were, no doubt, very persuasive. But they ought to yield now to scientific needs and particularly to the need to facilitate our progress in the understanding of nature.

With respect to animals which nature has succeeded in producing, so numerous and so varied, if we cannot boast of knowing exactly the true order which nature followed in bringing them successively into existence, what I am going to reveal is probably very close to that order. Reason and all the knowledge we have acquired encourage this probability.

In fact, if it is true that all living bodies are productions of nature, we cannot refuse to believe that she could produce them only successively, not all at once at a specific moment. Now, if she created them one after the other, there is reason

to believe that she began exclusively with the simplest and did not produce the most complex organic structures (in both the animal and plant kingdoms) until the end,

Botanists first gave zoologists the example of the true arrangement we should give to a general distribution in order to represent the very order of nature. For they formed the first class of plants with the acotyledonous or agamous plants, that is, with the structurally simplest plants, the most imperfect in every respect, in a word, with those which had no cotyledons, no determinable sex, no vessels in their tissues, plants which are, in fact, composed only of cellular tissue more or less modified according to different extensions.

What the botanists have done with respect to plants, we should finally do with the animal kingdom, not only because nature herself points in that direction and reason demands it, but also because the natural order of classes, according to the growing complexity in organic structure, is much easier to determine among the animals than it is with respect to plants.

While this order will better set down the order of nature, it will at the same time make the study of objects much easier, will improve our understanding of the organic structure of animals, the progress in its complexity from class to class, and will demonstrate even better the affinities existing between the different degrees in the make up of animal organization and the external difference which we most frequently use to characterize the classes, orders, families, genera, and species.

I add to these two considerations (whose basis one cannot seriously call into question) the fact that if nature, incapable of making organic structures which survive for

ever, had not had the means of giving these bodies the capacity of reproducing themselves with other individuals which resembled them, replaced them, and perpetuate the race by the same means, she would have been forced to create directly all the races or rather she would have been able to create only one race in each organic order, one for the simplest and most imperfect animals and one for the simplest and most imperfect plants.

In addition, if nature had not been capable of the active processes of organization with the ability to make that very organic structure more and more complex, by increasing the mobile energy of fluid movement and thus organic movement, and if she had not preserved through reproduction all the progress in the composition of organic structures and all the acquired improvements, she should assuredly never have produced this multitude of infinitely varied animals and plants, so different from each other in the condition of their organic structures and capacities.

Finally, she would not have been able to create right at the first the most eminent animal faculties, for they do not arise except with the help of very complex organic systems. Nature had to prepare gradually the means of bringing into existence such organic systems.

Thus, to establish, with respect to living bodies, the state of things which we observe, the only thing nature had to produce directly (that is, without the combination of any organic action) was the simplest organic bodies, whether animals or plants. And she still reproduces these in the same way, every day, in favorable places and seasons. Now, by giving to these bodies which she herself created the capacity

to feed themselves, to grow, to multiply, and to preserve each time the improvements they acquired in their organic structure and, finally, by passing on these same capacities to all the individuals produced by organic reproduction, over time, given the enormous diversity of always changing circumstances, the living bodies of all the classes and every order were, through these means, produced one after the other.

In considering the natural order of animals, the very marked gradation which exists in the growing complexity of their organic structure and the number as well as the improvement of their faculties is far from being a new truth, for even the Greeks were able to perceive it9. But they were not able to lay bare the principles and proofs, because people then lacked the knowledge necessary to establish them.

Now, in order to facilitate the knowledge of the principles which have guided me in the exposition which I am about to make concerning this order of animals, and to better render perceptible this gradation which we observe in the complexity of their organic structure, from the most imperfect among them, who are at the head of the series, right up to the most perfect which conclude the series, I have divided into six very distinct stages all the styles of organic structure which we have recognized in the entire extent of the animal ladder.

Of these six stages, the four first ones include the animals without vertebrae, and hence the first ten classes of the animal kingdom, according to the new order which we are

9 See the voyage of the Young Anacharsis, by J. J. Barthelemy, vol. V, p. 353 and 354.

going to follow; the two last stages include all the vertebrate animals, and thus the four (or five) final classes of animals.

With the assistance of this method, it will be easy to study and to follow the march of nature in the production of the animals she has brought into existence, to distinguish, throughout the whole extent of the animal ladder, the progress attained in the complexity of organic structure, and to verify throughout the precision of the distribution or the appropriateness of the assigned ranks, by examining the known characteristics and facts of organic structure.

This is the way in which for several years in my lessons at the Museum I set out the invertebrates, always proceeding from the most simple towards the most complex.

In order to make the arrangement and the totality of the general series of animals more distinct, let us first present a table of the fourteen classes dividing the animal kingdom, limiting ourselves to a very simple exposition of their characteristics and the stages of organic structure which they include.

Table of the Distribution and Classification of Animals,Following the order which conforms most closely to the order of natureINVERTEBRATE ANIMALSClassesI. THE INFUSORIANSAmorphous animals reproducing by fission or budding; gelatinous bodies, transparent, homogeneous, contractile and microscopic; no rayed tentacles or rotary limbs; no special organ, not even for digestion.

II POLYPSBudding, gelatinous regenerating bodies, without any internal organ other than an alimentary canal with only one opening. Terminal mouth, surrounded by radiating tentacles or furnished with ciliated and radiating organs. The majority form compound animals.

1st Stage

No nerves, no vessels, no special internal organs other than for digestion

III RADIATESFree suboviparous, with a regenerating body, lacking a head, eyes, articulated limbs, and having in its parts a radiating arrangement, a mouth underneath.

IV WORMSSuboviparous, with a soft regenerating body, not undergoing any metamorphosis, and never having eyes, nor articulated limbs nor a radiating arrangement in its interior parts.

2nd Stage

No knotty (ganglionic) longitudinal chord; no vessels for circulation; few interior organs other than those for digestion.

V INSECTSOviparous, undergoing metamorphoses and having, in the perfect state, eyes in the head, six articulated limbs, and tracheae which extend throughout; a single fertilization during a lifetime.

VI ARACHNIDSOviparous, with always articulated limbs and eyes in the head, not undergoing any metamorphosis; limited tracheae for respiration; rudimentary circulation; several fertilizations during a lifetime.

3rd Stage

Nerves ending in a knotty (ganglionic) longitudinal chord; respiration by aerated gills; circulation is absent or imperfect.

VII CRUSTACEANSOviparous, having articulated bodies and limbs; crustaceous skin, eye in the head, and most frequently four antennae; respiration by gills; a knotty (ganglionic) longitudinal chord.

VIII ANNELIDSOviparous, with elongated and annulated body; no articulated limbs; rarely eyes; respiration by gills; a knotty (ganglionic) longitudinal chord.

IX CIRRIPEDSOviparous, having an articulated mantle and limbs whose skin is horny, no eyes; respiration by gills, a knotty (ganglionic) longitudinal chord.

X MOLLUSKSOviparous, soft body, no articulation in its limbs. with a variable mantle; respiration by gills diversified in their form and their situation; no spinal chord, no knotty (ganglionic) longitudinal chord, but nerves ending in a brain.

4th Stage

Nerves ending either in a brain or in a longitudinal ganglionic chord; respiration by gills; arteries and veins for circulation.

VERTEBRATE ANIMALS

Classes

XI FISHOviparous and without teats; complete and constant respiration by gills; outline of two or four limbs; fins for movement; no hair or feathers on the skin.

XII REPTILESOviparous and without teats; incomplete respiration, most often by lungs which exist all the time or in later age; four limbs, or two, or none; no hair or feathers on the skin.

5th Stage

Nerves ending at a brain which does not fill the skull cavity; heart with one ventricle; cold blood.

XIII BIRDSOviparous and without teats; four articulated limbs, of which two are shaped into wings; respiration entirely by adhering pierced lungs; feathers on the skin.

XIV MAMMALSViviparous and with teats; four articulated limbs or only two; respiration entirely by lungs not pierced through to the exterior; hair on some parts of the body.

6th Stage

Nerves ending in a brain which fills the cranial cavity; heart with two ventricles; warm blood.

Such is the table of the fourteen classes established among the known animals, and arranged following the order which most closely approximates the order of nature. The arrangement of these classes is such that that we will always be forced to conform to it, even if we refuse to adopt the lines of separation which form them, because this arrangement is based on the analysis of the organic structure of the living bodies with which it deals. This consideration, of the first importance, establishes the affinities which exist among the objects making up each division and the rank of each one of these groups in the entire series.

People will never find solid reasons for changing this distribution in its entirety, for reasons which I am going to reveal. But we will be able to make changes in the details, and above all in the divisions subordinate to the classes, because the affinities between objects comprising the sub-divisions are more difficult to determine and assume a more arbitrary character.

Now, in order to make better understood how much this arrangement and distribution of animals conform to the very order of nature, I am going to reveal the general series of known animals, divided into its principal divisions, proceeding from the simplest towards the most complex, in accordance with the reasons indicated above.

My purpose, in this exposition, will be to put the reader in a position to recognize the rank, in the general series, occupied by the animals which, in the course of this work, I have often had occasion to refer to and to spare the reader the trouble of having to go to other works of zoology for that information.

However, I will give here only a simple list of genera and only of the principal divisions; but this list will be sufficient to demonstrate the extent of the general series, its arrangement conforming the most with the order of nature, and the indispensable placement of classes, orders, and thus, perhaps, of families and genera. We understand well that it is in the good works of zoology which we possess that we must study the details of all the objects mentioned in this list, because I have not taken that into consideration in this work.

General Distribution of AnimalsForming a series conforming to the very order of Nature

Invertebrate AnimalsThey do not have any vertebral column and

consequently have no skeleton; those which have points of support for the movement of parts have them under their teguments. They lack a spinal chord and present a great diversity in the complexity of their organic structure.First Stage of Organic Structure

No nerves, no longitudinal ganglionic chord, no vessels for circulation, no respiratory organs; no other special interior organ except for digestion.[The Infusorians and Polyps]

THE INFUSORIANS(First Class of the animal kingdom)

Fissiparous animals, amorphous, with gelatinous bodies, transparent, homogeneous, contractile and microscopic; no radiating tentacles; no rotary appendages; no special organ in the interior, not even for digestion.

ObservationsOf all the known animals, the infusorians are the most

imperfect, the simplest in organic structure, and those which possess the fewest capacities. It is certain they have no ability to feel.

Infinitely small, gelatinous, transparent, contractile, almost homogeneous, and incapable of having any special organ because of the excessively weak consistency of their parts, the infusorians are really only the rudiments of animal life.

These frail animals are the only ones which do not carry out digestion in order to nourish themselves and which, in fact, feed only by absorption through the pores of their skin and by an interior saturation.

In this matter they resemble the plants, which live only by absorption and carry out no digestion and whose organic movements operate only through external stimuli. But the infusorians are irritable and contractile, and they go through sudden movements which they can repeat several times in a row, something which characterizes their nature as animals and fundamentally distinguishes them from plants.

Table of InfusoriansFirst Order: Naked Infusorians

They lack external appendagesMonadsVolvoxProteusVibrio

------BursariaColpoda

Second Order: Infusorians with AppendagesThey have projecting parts, like hairs, types of horns or a tailCercariaTrichocercaTrichoda

Remarks. The monad, and especially the one which is called Monas termo, is the most imperfect and simplest of known animals, because its body, which is extremely small, displays only a gelatinous and transparent point, but it is contractile. This animal therefore must be considered the one at which the series of animals, organized according to nature, begins.

POLYPS(Second Class of the Animal Kingdom)

Gemmiparous animals, with gelatinous regenerating bodies, without any interior organ except an alimentary canal with a single opening. Terminal mouth surrounded by radiating tentacles or furnished with ciliated or rotatory organs. The majority adhere to each other, communicate together by their alimentary canal, and thus form composite animals.

ObservationsWe saw in the infusorians infinitely small, frail

animalcules without consistency, without a shape unique to their class, without any organs at all, and consequently without a mouth and a distinct alimentary canal.

In the polyps, the simplicity and imperfection of the organic structure, although still very noticeable, are less great

than in the infusorians. Organic structure has clearly made some progress, for already nature has given the animals of this class a consistently regular form; already they are furnished with a special organ for digestion, and consequently with a mouth, the entry to their alimentary sack.

If we picture for ourselves a small elongated body, gelatinous, very irritable, having at its upper extremity a mouth furnished either with rotatory organs or radiating tentacles which serves as the entry point to an alimentary canal which has no other opening, we will get an image of the polyp.

If we add to this idea the notion of the adherence of several of these small bodies, living together and participating in a common life, we will understand the most general and the most remarkable fact concerning these animals.

Since the polyps have neither nerves for feeling nor special organs for respiration nor vessels for the circulation of their fluids, they are the more imperfect in their organic structure than the animals which are going to follow.

Table of PolypsFirst Order: Rotifer Polyps

They have around their mouths ciliated and rotatory organsUrceolariaBrachionus (?)Vorticella

Second Order: Polyps in PolypariesThey have around their mouths radiating tentacles and are fixed in a polypary which does not float on the oceans.(1) Membranous or Horny polypary, without a distinct outer crust

CristatellaPlumatellaTubulariaSertularia

CellairiaFlustraCelleporaBotryllus

(2) Polypary with a horny axis, covered with a crustAcetabulaCorallina--------Sponge

AlcyonAntipataGorgona

(3) Polypary with an axis and partly or entirely stony, and covered over with a bark like crustIsisCoral(4) Polypary entirely stony without a crust

TubiporaLunulitesOvulitesSiderolitesOrbulitesAlveolitesOcellairiaEschara

PavoniaMeandrinaAstreaMadreporaCaryophyllliaTurbinoliaFungiaCyclolites

ReteporaAgricia

DactyloporaVirgularia

Third Order: Floating PolypsA polypary free, elongated, floating in water, and having a horny or bony axis covered with a skin common to all the polyps; radiating tentacles around the mouth.

FuniculinaVeretillumPennatula

EnerinusUmbellularia

Fourth Order: Naked PolypsThey have radiating often multiple tentacles at their mouths; they do not form polyparies.

PedicellariaCoryneHydra

ZoanthaActinia

Second Stage of Organic StructureNo longitudinal ganglionic chord, no vessels for

circulation; a few special internal organs (either tubes or pores taking in water or species of ovaries) other than those for digestion.

[The Radiates and Worms]RADIATES

(Third Class of the Animal Kingdom)Subgemmiparous animals, free or wandering; with

regenerating bodies, a radiating arrangement of parts, both internal and external, and compound organ of digestion;

lower mouth, simple or multiple. No head, no eyes, no articulated limbs; a few internal organs other than those for digestion.

ObservationsHere is the third line of classic separation which it is

useful to draw in the natural distribution of animals.Here we find entirely new forms which all nonetheless

have affinities with a common similar type, as follows: the radiating arrangement of the parts, both interior and exterior.

These are no long animals with an elongated body, an upper terminal mouth, usually established in a polypary with a great number of them living together, each participating in a communal life. These are animals with a more complex organic structure than in the polyps, simple, always free, with a design which is unique to them, and generally orienting themselves in an inverted position.

Almost all the radiata have tubes drawing in water which appear to be aquatic trachaea. And in a great number we find special bodies which look like ovaries.

In a Memorandum which I have just heard read in the assembly of professors at the Museum, I learn than a wise observer, Doctor Spix, a Bavarian physician, has discovered in the star fishes and sea anemones the apparatus of a nervous system.

Doctor Spix claims to have observed that in the red star-fish, under a membrane made up of tendons (like a tent) there is suspended on the stomach a reticular structure made up of whitish nodules and threads and, in addition, at the origin of each ray, two nodules or ganglia which

communicate with each other by a thread and from which other threads leave and go to parts close by; among others there are two very long threads which run through the full length of the ray and supply the tentacles.

According to the observations of this learned man, we see in each ray two nodules, a small extension of the stomach (coecum), two hepatic lobes, two ovaries and trachaeal canals.

In the sea-anemones, Dr. Spix observed at the base of these animals, below the stomach, a few pairs of nodules, arranged around a centre, which communicate with each other by cylindrical threads and which send out other threads to the upper parts. Moreover, he saw there four ovaries surrounding the stomach, from the base of which canals leave which, after joining up, open into a lower point of the alimentary canal.

It is astonishing that such a complex organic apparatus has escaped the attention of all those who have examined the organic structure of these animals.

If Doctor Spix was not imagining things in in what he believed he saw and if he was not wrong in attributing to these organisms a nature and functions different from what is appropriate to them (something which has happened to so many botanists who believed they saw male and female organs in almost all the cryptogram plants), then the consequences are as follows:

(1) It is not in the insects that we must establish the commencement of a nervous system;

(2) This system must be considered as rudimentary in the insects, radiates, and even in the sea-anemone, the last genre of polyps;(3) This is not a reason why all polyps should possess the rudiments of this system, in the same way that it does not follow that all reptiles are equipped with bills just because some have them.(4) Finally, the nervous system is no less a special organ, not shared by all living bodies. For not only is it irrelevant in plants but it it is not even present in all the animals. As I have made known, it is impossible that the infusorians are furnished with a nervous system and assuredly polyps in general are not capable of having one. Thus, we would look for it in vain in the hydras, which nonetheless belong to the last order of polyps, the one closest to the radiates, since it includes the sea anemones.Thus, whatever the basis for the facts cited above, the

points which I present in this work on the successive formation of the different special organs remain valid no matter at what point in the animal scale each of these organs originates. And it is always the case that the abilities which the organs provide for the animal do not begin to operate until the organ which provides them come into existence.

Table of RadiatesFirst Order: Soft Radiates

Gelatinous body; soft skin, transparent, lacking articulated spines; no anus.

StephanomiaLucernariaPhyssophoraPhysaliaVelellaPorpita

PyrosomaBeroeAequoreaRhizostomaMedusa

Second Order: Echinoderm RadiatesOpaque skin, crustaceous or coriaceous, furnished with retractable tubercules or articulates spines on tubercules, and pierced with holes in a series.(1) Stellerides. Skin not irritable, but mobile; no anusOphiuraAsteria

(2) Echinoids. Skin not irritable, not mobile; an anusClypeasterCassiditesSpatangusAnanchytes

GaleritesNucleoitesSea urchin

(3) Fistulides. Elongated body, an irritable and mobile skin; an anusHolothuriaSipunculus

Remarks. The sipunculus are animals very close to worms. However their known affinities with the holothuria have led them to be placed among the radiates, with which they no longer share characteristics. Consequently, they must come at the end.

In general, in a really natural distribution, the first and the last genera of classes are those in which the classical characteristics are less pronounced. Because they come at the limits of the class and the lines of separation are artificial, these genera must display to a lesser extent than the others the characteristics of their class.

WORMS(Fourth Class in the Animal Kingdom)

Suboviparous animals, with soft elongated bodies, without a head, eyes, limbs, or bunches of setae; without circulation and with a complete intestinal canal (one with two openings). Mouth made up of one or several suckers.

ObservationsThe general form of worms is very different from that

of the radiates. Their mouths, always a sucker, has no similarity to those of the polyps, which display only an aperture accompanied by radiating tentacles or rotatory organs.

Worms have, in general, an elongated body, very slightly contractile, although very soft, and their intestinal canal is not limited to a single opening.

In the fistulid radiates, nature began to abandon the radiating form of the parts and to give animal bodies an elongated shape, the only one which might lead to the goal which nature set for herself.

Once nature created the worms, she is going to tend from that point on to establish the pattern of the paired symmetry of parts, which she could not attain except by an articulated design. But in the class of worms, which is

ambiguous to some extent, she has only sketched out a few traits.

Table of WormsFirst Order: Cylindrical Worms

DragoneauFiariaProboscideaCrinoAscarisFissulaTrichocephaus

CucullanusStrongyiusScolexCaryophyllacusTentaculariaEchinorhyncus

Second Order: Bladder WormsBicornHydatis

Third Order: Flat WormsTaeniaLinguatula

LingulaFasciola

Third Stage of Organic StructureNerves ending in a longitudinal ganglionic chord;

respiration by aerated trachaea; no circulation (or imperfect).[The Insects and Arachnids]

INSECTS(Fifth Class of the animal kingdom)

Oviparous animals, undergoing metamorphoses, able to have wings, and possessing, in the perfect state, six

articulated limbs, two antennae, two faceted eyes, and a horny skin. Respiration by aerated trachaea which extend to all the parts; no system of circulation; two distinct sexes; one single reproductive act in a lifetime.

ObservationsHaving reached the insects, we find among the

extremely numerous animals which this class includes a very different order of things from the classes which we have have encountered in the animals of the four preceding classes. Moreover, in the place of modulations in the progressive complexity of the organic structure in animals, once we arrive at the insects, in this matter we have made quite a considerable leap.

Here, for the first time, the animals examined from the outside show us a true head which is always distinct, very remarkable eyes (although still very imperfect), articulated limbs arranged in two rows, and the symmetrical form of paired and opposing parts which nature will use from this point on right up to and including the most perfect animals.

When we move to the interior of insects, we see in addition a complete nervous system, consisting of nerves which end a a longitudinal ganglionic chord. Although complete, this nervous system is still very imperfect. The area where the sensations meet appears very fractured, and the senses themselves are few and very obscure. Finally, we see in the interior of the insect a real muscular system and distinct sexes, which, however, can provide only a single fertilization (as with the plants).

True, we do not yet find a circulatory system, and it is necessary to go higher in the animal chain to find this improvement in organic structure.

The property of all insects is having wings in their perfect state, so that those which lack them have been deprived only by an abortion which has become habitual and constant.

ObservationsIn the table which I am going to present, the genera

have been reduced to a number considerably lower that that of the genera which people have made from the animals in this class. Interest in studying the subject and the simplicity and the clarity of the method seemed to me to demand this reduction, which is not going to harm at all an understanding of the objects. To use all the particular details which one could seize upon in the characteristics of animals and plants in order to multiply genera to infinity is, as I have already said, to clutter up and obscure science instead of serving it. It makes the study of science so complicated and difficult, that it would become impossible to practice it, except for those who wished to dedicate their entire lives to learning the immense nomenclature and the minute characteristics used to make distinctions among animals.

Table of InsectsA. SUCKING INSECTS

Their mouths display a sucker furnished or lacking a sheathFirst Order: Apterous Insects

A proboscis with two valves and articulated in three places, containing a sucking organ with two bristles The wings have

usually aborted in both sexes; legless larvae; immobile nymph in a cocoon.Flea

Second Order: Dipterous InsectsA non-articulated proboscis, straight or with an elbow, sometimes retractile. Two bare wings membranous and veined; two balancers; vermiform larvae, most often without feet

Hippobosca (Horse Fly)Oestrus-------StratiomysSyrphusAnthraxFly-------StomoxeMyopaConops

------EmpisBombylusAsilusTaonRhagio-----CousinTipulaSimuliumBibio

Third Order: Hemipterous InsectsSharp articulated beak, curved under the chest serving as a sheath for a sucker with three bristles. Two wings hidden under membranous elytra; larvae with six feet; the nymph moves and eats.

DorthesiaCochineaPsyllaAphidsAleyrodesThrips------CicadaFulgoraTettigonia------Scutellera

PentatomaBed BugsCoraeusReduviusHydrometraGerris------NepaNotonecteNancorisCorixa

Fourth Order: Lepidopterous InsectsA two-part sucker, lacking a sheath, like a tubular proboscis, and folded up as a spiral when inactive. Four membranous wings, covered with colour scales like flour. The larvae have eight to sixteen limbs, inactive chrysalis.(1) With subulate or setaceous antennae

PetrophorusOrneodesCerastomaTineaNoctuaPhalaena

AlucitaAdellaPyralis------HepialusBombyx

(2) Antennae swollen somewhere along their lengthZygoenaButterfly

SphinxSesia

(B) BITING INSECTSTheir mouths display mandibles, most often accompanied by jaws

Fifth Order: Hymenopterous InsectsMandibles and a three-sectioned sucker more or less extended, the base of which is enclosed in a short sheath. Four bare wings (membranous, veined, unequal); in the female the anus is equipped with a sting or apparatus for boring; immobile nymph.(1) Females equipped with a sting in the anus

BeeMonomelitesNomadsEuceraAndrena-----WaspPolistes

AntMutillaScoliaTiphiaBembexCrabroSphex

(2) Females equipped with a boring apparatus in the anusChrysisOxyurus-----LeucopsisChalcisCinipsDiplolepisIchneumon

-----EvaniaFoene------UrocereOryssusTenthredoClavellair

Sixth Order: Neuopterous InsectsMandibles and jaws; four naked wings (membranous and reticulated); lengthened abdomen, lacking a sting or boring apparatus; six-footed larva; variation in the metamorphoses.(1) Inactive nymphs

PerlaNemouraFrigania

HemerobiusAscalaphusMyrmeleon

(2) Active nymphsNemoptereaPanorpaPsocusTermes-----CorydalisChauliodes

RaphidiaEphemera-----AgrionAeshnaLibellula

Seventh Order: Orthopterous InsectsMandibles, jaws, and galeae covering the jaws; two straight wings, longitudinally folded and cover by two almost membranous elytra; larvae as in the perfect insect, but having neither wings nor elytra; active nymph.

GrasshopperAchetaLocustTruxalis----Mantis

PhasmaSpectrum------CricketCockroachEarwig

Eighth Order: Coleopterous InsectsMandibles and jaws; two membranous wings, transversely folded in repose and under two hard or coriaceous shorter elytra; six-footed larvae; scaly head and eyeless; inactive nymph.(1) Two or three parts in every tarsal

Pselaphus-----

Lady-birdEumorphus

(2) Four parts in every tarsalErotylusCassidaChrysomelaGalerucaLepturaStencorusSaperdaNecydalisCallidiumCerambixSprionusSpondilus-----Bostrichus

CriocerisClythraGriborus-----MycetophagusTrogossitaCucujus-----BruchusAttelabusBrentusCurculioBrachycerus

(3) Five parts in the tarsals of the first pair of feet and four on those of the third pair.

OpatrumTenebrioBlaps

MomrdellaRhipiphorusPyrochroa

PimeliaSepidiumScaurusErodiusChiroscelis-----HelopsDiaperis-----Cistela

CossiphusNotoxusLagriaCercomaApalusHoriaMylabrisCantharisMeloe

(4) Five parts on every tarsalLymexylonTelephorusMalachiusMelyrisLampyrisLycusOmalysusDrilus-----MelasisBuprestisCLick beetle-----PtinusDeath-watchPtinus-----StaphylinusIps.

OxyporusPoederus-----CicindelaElaphrusScaritesManticoraCarabusDyticus-----HydrophilusGyrinusDryopsClerus.-----NecrophorusCarrion-beetleNitidulaGoliathusCockchafter

DermestesAnthrenusByrrhusHister.Sphoeridinus-----Trox.Cetonia

LethrusGeotrupesCoprisScarabaeusPassalusLucanus

ARACHNIDS(Sixth Class of the Animal Kingdom)

Oviparous animals, always having articulated limbs and eyes in the head; they do not undergo a metamorphosis and never possess wings or elytra; stigmata and limited trachaea for respiration; a rudimentary circulation system; several fertilizations in a lifetime.

ObservationsThe arachnids, which in the order which we have

established come after the insects, show clear progress in the perfecting of organic structure.

In fact, sexual reproduction manifests itself with the arachnids, for the first time, with all its capabilities, since these animals couple and reproduce several times in their lives, while in the insects, the sexual organs, like those of plants, can carry out only a single fertilization. Moreover, the arachnids are the first animals in which the circulation system begins to become sketched out. For according to the observations of Cuvier, we find in them a heart extending from which, on the sides, are two or three pairs of vessels.

The arachnids live in the air, like those insects which have reached the perfect condition But they do not undergo any metamorphosis, never have wings and elytra, something which is not the result of some abortion, and they remain, in general, hidden or living by themselves, feeding themselves on prey or by sucking blood.

In the arachnids, the method of respiration is still the same as in the insects, but the method is on the point of changing. For trachaea of arachnids are very limited (impoverished, as it were) and do not extend to all the parts of the body. These trachaea have been reduced to a small number of vesicles, something else Cuvier has taught us (Anatom., vol, IV, p. 419); and after the arachnids, this method of respiration does not occur again in any of the classes of animals which follow.

This class of animals needs to treated with care . Many of them are venemous, especially those which live in hot climates.

Table of ArachnidsFirst Order: Arachnids Pedipalyps

No antenna, only pedipalps; the head fused with the thorax; eight limbs

MygaleSpiderPhrynusThelyphnusScorpion-----Pince

TrogulElaisTrombidium-----HydrachnaBdellaMite

GaleodesFaucheur

NymphonPycnogonum

Second Order: Arachnids with AntennaTwo antennae; a head distinct from the thorax

LouseRicinus-----ForbicinaPodure

-----ScolopendreScutigeraJulus (millipede)

Fourth Degree of Organic StructureNerves terminating in a longitudinal ganglionic chord

or in a brain without a spinal chord; respiration with gills; arteries and veins for circulation.

[The Crustaceans, the Annelids, the Cirripeds and the Mollusks]

CRUSTACEANS(Seventh Class of the Animal Kingdom)

Oviparous animals, having articulated bodies and limbs, a crustaceous skin, several pairs of jaws, eyes and antennae in the head; respiration by gills; a heart and vessels for circulation.

ObservationsSome significant changes in the organic structure of

the animals of this class indicate that in forming the crustaceans nature has succeeded in making considerable progress in the organic structure of animals.

First, the method of respiration is here entirely different from that used in the arachnids and insects. And this method, made up of organs called gills, is going to continue right up to the fish. Trachaea do not appear again, and the gills themselves will disappear when nature is able to create a cellular lung.

Then, the circulation (which in the arachnids consists of only a simple outline) is fully established in the crustaceans, where we see a heart and arteries for sending out blood to the different parts of the body and veins which bring this fluid back to the principal organ responsible for its motion.

We find again in the crustaceans the style of articulations which nature has universally used in the insects and the arachnids, to facilitate muscular movement with the help of indurations of the skin, but from this point on nature will abandon this method of setting up an organic structure which no longer will require it.

The majority of crustaceans live in water, either fresh or brackish or salt. Some nonetheless remain on the earth and breathe air with their gills. All of them feed only on animal material.

Table of CrustaceansFirst Order: Sessile-Eyed Crustaceans

Sessile and immobile eyesWood-louseLigiaAsellusCyamus

CephaloculusAmymoneDaphniaLunceus

ShrimpCaprella-----CyclopsZoea

OsoleLimulusColigusPolyphemus

Second Order: Stalk Eyed CrustaceansTwo distinct eyes raised on mobile stalks(1) Elongated tail, equipped with swimming blades or hooks or hairs

BranchiopodSquillaPalaemonGalatheaEcrevissaPagurus (hermit crab)-----Ranina

CrangonPalinurus (rock lobster)ScyllarusAlbuneaHippiaCorystesPorcellana

(2) Short tail, bare, and held against the under part of the abdomen

PinotheresLeocosiaArctopsisMaia-----OrithyiaPodophtalmusPortunus

DorippePlagusiaGrapsusOcypodeCalappaHepatusDromiaCancer

ANNELIDS(Eighth class of the Animal Kingdom)

Oviparous animals with an elongated body, which is soft and ringed laterally, rarely having eyes and a distinct head, and lacking articulated limbs. Arteries and veins for circulation; respiration by gills; a longitudinal ganglionic chord.

ObservationsWe see in the annelids that nature is forced to abandon

the method of articulation which she has constantly used with the insects, arachnids, and crustaceans. Their bodies--elongated, soft, and for the most part composed of simple rings--gives these animals the appearance of being just as imperfect as the worms, with whom people have confused them. But since they have arteries and veins and breathe by gills, these animals, very distinct from the worms, must, along with the cirripeds, make the transition from the crustaceans to the mollusks.

They lack articulated limbs10, and most of them have, on the side, bristles or bundles which take the place of limbs. Almost all of them are suckers and feed themselves only on fluid material.

10 In order to perfect the organs of movement for the animals, nature had to leave off the system of articulated limbs, which are not the result of a skeleton, in order to establish the system of four limbs dependent on an interior skeleton which is unique to the most perfect animals. This is what nature has carried out in the annelids and the mollusks, where she has set about preparing the methods to begin, in the fish, the organic structure specific to vertebrate animals. Thus, in the annelids, she has abandoned articulated limbs, and in the mollusks has done even more: she has ceased to use a longitudinal ganglionic chord.

Table of AnnelidsFirst Order: Cryptobranch Annelids

PlanariaLeechLerniaClevella-----

Furia (?)NaisLumbricusThalassema

Second Order: Gymnobranch AnnelidsArenicolaAmphinomaAphroditeNereis-----TerebellaAmphitrite

Sabellaria-----SerpulaSpirorbisSiliquariaDentaliium

Cirripeds(Ninth Class of the Animal Kingdom)

Oviparous and testaceous animals without a head and eyes, having a mantle which covers the inside of the shell, articulated arms with a horny skin, and two pairs of jaws in the mouth; respiration by gills; a longitudinal ganglionic chord; vessels for circulation.

ObservationsAlthough we know only a small numbers of general

which are linked to this class, the characteristics of the animals which make up these genera are so remarkable that it

is necessary that we distinguish them as making up a specific class.

The cirripeds have a shell, a mantle, and have no head or eyes. Thus they cannot be crustaceans. Their articulated arms mean that we cannot place them among the annelids. And their longitudinal ganglionic chord prevents us from combining them with the mollusks.

Table of CirripiedsTubicinellaCoronula

BalanusAnatifa

Remarks: We see that the cirripeds still incline towards the annelids by their longitudinal ganglionic chord. But in these animals, nature is preparing itself to create the mollusks, because they already have, as do the latter, a mantle which covers the interior of their shell.

Mollusks(Class Ten of the Animal Kingdom)

Oviparous animals, with a soft body (not articulated in its parts) and a variable mantle; respiration by very diversified gills; no spinal chord, no longitudinal ganglionic chord; nerves ending at an imperfect brain.

Most of them are enveloped in a shell; others have a shell more or less entirely enclosed in their interior; and still others have no shell at all.

ObservationsThe mollusks are the best organized of the animals

without vertebrae, that is to say, those whose organic structure is is the most complex and which come closest to that of fish.

They make up a numerous class which ends the invertebrates and which is really distinguished from the other classes, since the animals which make it up have a nervous system, like many others, but are the only ones which have neither a longitudinal ganglionic chord nor a spinal chord.

Nature, at the point of starting to form the system of organic structure of the vertebrate animals, appears here to be preparing herself for this change. Thus the mollusks, which have no link any more to the style of articulation and of the attachment which a horny skin gives for the muscles of animals who have this feature, are very slow in the movements and appear, in this respect, more imperfectly structured than even the insects.

Finally, since the mollusks make the transition from invertebrates to vertebrate animals, their nervous system is intermediate, and displays neither the longitudinal ganglionic chord of the invertebrate animals with nerves nor the spinal chord of the vertebrate animals. This is eminently characteristic of them and clearly distinguishes them from the other invertebrates.

Table of MollusksOrder One: Acephalic Mollusks

No head, no eyes, no organs for chewing; they reproduce without copulation; most of them have a shell with two valves which articulate with a hinge.BrachiopodsLingulaTerebratulesOrbiculesOstracians

RadiolitesCalceolaCraniaAnomiaPlacunaVulsella

OysterGryphaeaPlicatulaSpondylusPecten

ByssiferaHouletteLimaPinnaPernaMalleus

MytilusModiola (?)CrenatulaAvicula-----

ChamaceansEtheriaChamaDiceras

CorbulaPandora-----

NaiadsMuletteAnodontaArcaceans

NuculaPetunculusArca

CucullaeaTrigonia-----

CardiadsTridaenaHippopusCardita

IsocardiaCardium

ConchsVenericardiaVenusCythereaDonaxTellina

LucinaCyclasGalatheaCapsa

MactraceansErycinaUngulinaCrassatella

LutrariaMactra-----

MyariansMyaPanorpsAnatina

SolenaceansGlycimeriaSolenSanguinolaria

PetricolaRupellariaSaxicava

PholadariansPholasTeredoFistulana

Aspergillum-----

AscidiansAscidiaSalpaMammaria

Order Two: Cephalic MollusksA distinct head, eyes and two or four tentacles in most, jaws or a proboscis by the mouth; reproduction by coupling; the shell in those which have one never consists of two articulated valves with a hinge.

(1) PteropodsTwo opposed fins for swimmingHylaeaClioPneumoderma(2) Gasteropods(A) straight body, unified to the foot in all or almost all its length.

TritoniansGlaucusAeolisScyllaea

TritoniaTethysDoris

PhyllidiansPleurobranchusPhyllidiaChiton

PatellaFissurellaEmarginula

LaplysiansLaplysiaDolabella

BullaeaSigaretus

LimaciansOnchidiumLimaxParmacella

VitrinaTestacella-----

(B) Spiral body; no siphon Colymaceans

Helix (snail)HelicinaBulimus

AmphibulimusAgathinaPupa

OrbaceansCyclostomaVivipara

PlanorbisAmpullaria

AuriculaceansAuriculaMelanopsis

MelaniaLimnaea

NeritaceansNeritinaNavicella

NeritaNatica

StomataceansHaliotisStomatiaStomatellaTurbinaceans

PhasianellaTurboMonodontaDauphinula

ScalariaturritellaVermicularia(?)

HeteroclitesVolvariaBullaJanthinaCalyptraceans

CrepidulaCalyptraea

SolariumTrochus

(c) Spiral body, a siphon

CanaliferaCerithiiumPleurotomaTurbinellaFasciolaria

PyrulaFususMurex

Wing ShellsRostellariaPeterocerasStrombusPurpuraceans

CassisHarpaDoliumTerebraEburna

BuccinumConcholepasMonocerosPurpuraNassa

ColumellariansCancellariaMarginellaColombella

MitraVoluta

ConvolutesAncillaOlivaTerebellum

OvulaCypraeaConus

(3) Cephalopods(A) with multilocular testLenticulaceans

MiliolaGyrongonitaRotaliaRenulites

DiscorbinaLenticulinaNummulites

LituolaceansLituolitesSpirolinitesSpirula

OrthoceraeHippuritesBelemnites

NautilaceansBaculitesTerrilitesAmmonoceras

AmmonitesOrbulitesNautilus

(B) With unilocar testArgonautaceansArgonautaCarinaria(C) Without testSepialeansOctopusCalamaryCuttle-fish

VERTEBRATESThey have a vertebral column made up of a multitude

of short bones, articulated and arranged in a linear sequence. This column serves to hold up the body, establishes the basis of the skeleton, provides a sheath for the spinal chord, and terminates at the anterior end with a bony container which contains the brain.

FIFTH stage of Organic StructureNerves ending at a spinal column and at a brain which

does not fill the skull cavity. The heart has one ventricle and cold blood.

[The Fish and the Reptiles]The Fish

(Class Eleven of the Animal Kingdom)Oviparous animals, vertebrate and with cold blood;

living in water, breathing by gills; covered with a skin, either scaly or almost bare and viscous, and having for movement only membranous fins, held up by a bony or cartilaginous framework.

ObservationsThe organic structure of fish is much more perfected

than that of mollusks and of the animals of the preceding classes, since they are the first animals which have a vertebral column, the outline of a skeleton, a spinal chord, and a skull enclosing the brain. They are also the first in which the muscular system derives its points of attachment from interior parts.

However, their respiratory organs are still analogous to that in the mollusks, cirripeds, annelids, and crustaceans. And like all the animals of the preceding classes, they still lack a voice and have no lids on the eyes.

The form of their body is appropriate for their need to swim, but they keep the paired symmetrical shape of their parts (which began in the insects); finally, with them, as well as with the animals of the three following classes, the style of articulation is only on the inside and only occurs in the parts of their skeleton.

Note. For the creation of the table of vertebrates, I used the work of Dumeril, entitled Analytical Zoology, and I permitted myself only a few changes in the arrangements of items.

Table of FishOrder One: Cartilaginous Fish

Soft vertebral column, like cartilage; no true ribs in many of them.(1) No opercule and no membrane over the gillsTrematopneansRespiration by round holes1. CyclostomesGasterobranchus (hagfish, myxine)Lamprey

2. PlagiostomesTorpedoSkateRhinobatus

SquatinaSqualusAodon

(2) No opercule over the gills, but a membraneChismopneansOpenings of the gills by slits on the sides of the neck; four paired fins3. . . . . . . . . . . .

BatrachusLophius

BalistesChimaera

(3) An operculum above the gills but no membraneEleutheropomesFour paired fins; mouth under the muzzle4. . . . . . . . . . . .PolyodonPegasusAccipenser (Sturgeon)(4) An operculum and a membrane over the gillsTeleobranchescomplete gills, having an operculum and a membrane5. AphyostomesMacrorhyncusSolenostomaCentriscus (snipe fish)

6. PteropteraCyclopterus (lump sucker)Lepadogaster7. Osteoderms

OstracionTetraodonOvoidea

DidonSpheroidonSyngnathus

Order Two: Bony FishVertebral column with inflexible bony vertebrae(1) An operculum and an membrane over the gillsHolobranchsApode HolobranchsNo paired lower fins8. Peropterous holobranchs

CoeciliaMonoopterusLeptocephalusGymnotusTrichurus

NotopterusOphisurusApteronotusRegalecus

9. Pantopterous holobranchsMuraenaAmmodytesOphidiumMacrognathusXiphias

AnarrhichasComephorusStromataeusRhombus

Jugular Holobranchspaired lower fins situated under the throat, anterior to the thoracic fins10. Auchenopterous Holobranchs

MurenoidCalliomorusUranscopusWeaverCod

BatrachoidesBlennyOligopodKurtusChrysostrome

Thoracic Holobranchspaired lower fins situated under the pectorals11. Petalosome Holobranchs

LepidopusCepolaTaenoid

BostrichthysBostrichoidGymnetrus

12 Plecopod HolobranchsGobiusGobioid13. Eleutheropod HolobranchsGobiomoreGobiomoroidEcheneis14. Atractosome Holobranchs

ScomberScomberoidCaranx

ScomberomorusGasterosteusCentropodus

TrachinoteCaranxomorusCaesioCaesiomorus

CentronotusLepisacanthusIstiophorePomatome

15 Leipome HolobranchsHistulaCorisGomphosusOsphronemusTrichopodMonodactylPlectorhincusPaogoniasLabrus

ChilinusCheilodipteronOphicephalusHologymnosaSparusDipterodonCheilioMullet

16. Osteostome HolobranchsScarusOstorhincusLeignathus17. Lophionotous Holobranchs

CoryphaenaEmipteronotaCoryphaenoid

TaenionotusCentrolophusEques

18. Cephalotous HolobranchsGobiesoxAspidophoraAspidophoroides

CottusScorpaena

19. Dactylous HolobranchsDactylopterusPrionotus

TriglaPeristedion

20. Heterosome HolobranchsPleuronectesAchirus21. Acanthopome Holobranchs

LutjanusCentropomusBodianusTaenianotus

SciaenaMicropterusHolocentrumPerca

22. Leptosome HolobranchsChetodonAcanthinionChetodipteronPomacentrusPomadasisPomacanthusHolacanthusEnoplosusGlyphisodon

AcanthurusAspisurusAcanthopodSeleneArgyriosusZeusGaleoidesChrysostoseCapros

Abdominal HolobrachsPaired lower fins placed a little in front of the anus23. Siphonostome Holobranchs

FistulariaAulostomaSolenostoma24 Cylindrosome Holobranchs

CobitisMisgurnusAnablepsFondulusColumbrine

AmiaButirinusTripteronotusOmpolk

25. Oplophore HolobranchsSilurusMacropteronotusMalapterurusPimelodusDorasPogonathusCataphractusPlotosus

AgenicsusMacrorhamphosusCentranodonLoricariaHypostomeCorydorasTachysurus

26. Dimerid HolobranchsCirrhitesCheilodactylus

PolynemusPolydactylus

27. Lepidome HolobranchsMugilMugiloid

ChanosMugilomorus

28. Gymnopome HolobranchArgentinaAtherinaHydrargyrusStolenphorusBuroClupeaMystus

ClupanodonGasteropleucusMeneDorsuariaXysteraCyprinus

29. Dermopterous HolobranchsSalmoOsmerisCorregonus

SharacinusSerrasalmo

30. Siagonote HolobranchsElopsMegalopsEsoxSynodon

SphyraenaLepisosteusPolypterusScombresox

(2) An opercule over the gills but no membrane.STERNOPTYGES31. . . . . . . . . . . . .Sternoptyx(3) No opercule over the gills, but a membrane32. . . . . . . . . . . .MormyrusStylophorus

(4) No operculum nor membrane over the gills; no paired lower finsOPHICHTHIANS33. . . . . . . . . . .

Unibranch apertureSphagebranchus

MurenophisGymnomuraena

Remarks. Since the skeleton started to form itself in the fish, those called cartilaginous are probably the least perfected fish, and consequently the most imperfect of all must be the gasterobranch which Linnaeus, under the name myxine, considered a worm. Thus, in the order which we are following, the genus gasterobranch must be the first of the fish, because it is the least perfected.

REPTILESViviparous animals, with vertebra and cold blood;

breathing incompletely by a lung, at least in their later life; with a smooth skin or one covered in scales or a bony shell.

ObservationsIn the reptiles some progress in the perfectioning of

organic structures is very noticeable, if we compare these animals with the fish. For among them we find for the first time the lung, which we know is the most perfect respiratory organ, because it is the same as what is in man. But here it is only sketchy, and several reptiles do not even have one in the early part of their lives. In truth, they breathe only incompletely, for only a part of the blood is sent to the parts which go by the lung.

It is also among them that we see for the first time in a distinct way four limbs which are part of the design of vertebrate animals and which are appendages of (or depend upon) the skeleton.

Table of ReptilesFirst ORDER: BATRACHIAN REPTILES

Heart with one auricle; bare skin; two or four legs; gills in the first stage of life; no couplingUrodela

SirenProteus

TritonSalamander

AnuraTree-frogFrog

PipaToad

SECOND ORDER: OPHIDIAN REPTILES (SNAKES)Heart with one auricle; elongated body, narrow and without limbs or fins; no eyelidsHomoderms

CoeciliaAmphisboenaAcrochordus

OphisaurusSlow-wormSea snake

HeterodermsCrotalusScytaleBoa

ErixViperColuber

Erpeton Platurus

THIRD ORDER: SAURIAN REPTILESHeart with two auricles; scaly body furnished with four limbs; claws on the digits; teeth in the jaw bones.Tereticauds

CalcidesScincusGeckoAnolisDragon

AgamaLacertaIguanaStellioChamaeleon

PlanicaudsUroplatesTupinambisBasiliseus

LophuraDracaenaCrocodile

FOURTH ORDER: CHELONIAN REPTILESHeart with a double auricle; body equipped with a carapace and four limbs; no teeth in the jaw bones

CheloniaChelys

EmysTortoise

SIXTH DEGREE OF ORGANIC STRUCTURENerves ending at a spinal chord and a brain which fills

the cranial case; heart with two ventricles and warm blood.[Birds and Mammals]

BIRDS(Thirteenth Class of the Animal Kingdom)

Oviparous animals, vertebrates and with warm blood; breathing completely by adhering and pierced lungs; four articulated limbs, two of which are shaped as wings; feathers on the skin.

ObservationsThe birds certainly have an organic structure more

perfect than the reptiles and all the animals of the preceding classes, because they have warm blood, a heart with two ventricles, and their brain fills the cranial case, characteristics which they share only with the more perfect animals which make up the last class.

However, birds evidently form only the penultimate rung of the animal ladder, for they are less perfect than the mammals, since they are still oviparous, lack mammary glands, lack a diaphragm, a bladder, and so on, and since they have fewer faculties.

In the table which follows, one can notice that the four first orders include the birds whose young cannot walk or feed themselves when they hatch and, by contrast, the three last orders include the birds whose young move and feed themselves as soon as they emerge from the egg. Finally, the seventh order, that of the palimpeds, seems to me to show

birds who, through their affinities, come closest to the animals of the class which follows.

Table of BirdsFirst order: climbers

To digits in front and two at the back.Levirostrate Climbers

ParrotCockatooMacawPull-bird

TouracoTrogonMusophagaToucan

Cuneirostrate ClimbersWoodpeckerWryneckJacamar

AniCuckoo

SECOND ORDER: RAPTORSA single digit at the back; anterior digits completely free; hook beak and clawsNocturnal RaptorsOwlEagle-owlSurniaBare-Neck RaptorsCondorVulture

Feather Necked RaptorsGriffonSecretary-birdEagle

BuzzardGoshawkFalcon

THIRD ORDER: PASSERESA single digit at the back; the two front external digits are united; the tarsus of medium heightCrenirostrate Passeres

TanagraShrikeFlycatcher

AmpelisThrush

Dentirostrate PasseresHornbillMotmotPhytotomaPlenirostrate Passeres

GrackleBird-of-ParadiseRoller

CrowPie

Conirostrate PasseresOx-peckerBlaucopisOrioleCacicusStarling

CrossbillBrosbeakColiusFinchBunting

Subulirostrate PassaresMannakinTitmouse

LarkWagtail

Planirostrate PassaresMartinSwallowNightjarTenuirostrate Passares

KingfisherTodyNuthatchOrthorincus

Bee-eaterHumming-birdCreeperHoopoe

FOURTH ORDER: COLUMBAESoft flexible beak, flat at the base; nostrils covered my a soft skin; wings appropriate for flight; brood of two eggsPigeon

FIFTH ORDER: GALLINACEANSSolid beak, horny, rounded at the base; brood of more than two eggsAlectride Gallinaceans

BustardPeacockTetrasPheasant

Guinea-fowlCurassowPenelopeTurkey

Brachypterous GallinaceansDodoCassowary

RheaOstrich

SIXTH ORDER: WADERSVery long tarsus, without feathers right up to the leg; external digits united at their base (birds of the water's edge)Pressirostrate Waders

JacanaRailOyster-catcher

MoorhenCoot

Cultrirostrate WadersBitternHeronStork

CraneMycteriaTantalus

Teretirostrate WadersAvocetCurlewWoodcock

DunlinPlover

Latirostrate WadersBoatbillSpoonobillPheonicopterus

SEVENTH ORDER: PALIMPEDSDigits linked by large membranes; tarsus not very high (aquatic animals, swimmers)

Penniped PalimpedsAnhingaPhaetonGannet

Frigate-birdCormorantPelican

Serrirostrate PalmipedsMerganserDuckFlamingoLongipen Palmipeds

GullAlbatrossPetrel

AvocetTernScissor-bill

Brevipen PalimpedsGrebeGuuillemotAuk

PenguinKing-penguin

MONOTREMES (Geoff.)Animals intermediate between the birds and the mammals; these animals are quadrupeds, without mammary glands, without teeth in the jaws, without lips, and with only one orifice for the genital organs, feces and urine; their body is covered with hair or bristlesOrnithorhynchusEchidna

Note: I have already spoken of these animals in Chapter VI, where I showed that they are neither mammals, nor birds, nor reptiles.

MAMMALS(Fourteenth Class of the Animal Kingdom)

Viviparous animals with mammary glands; four articulated limbs, or only two; respiration entirely by lungs which are not pierced on the outside; hair on some parts of the body.

ObservationsIn the order of nature, which clearly proceeds from the

simplest towards the most complex in its workings on living bodies, the mammals necessarily make up the last class of the animal kingdom.

This class effectively includes the most perfect animals, those which have the most faculties, the most intelligence, and finally, the most complex organic structure.

These animals whose structure comes closest the that of man display for this reasons a combination of senses and faculties more perfect than all the others. They are the only ones which are truly viviparous and which have mammary glands to suckle their young.

Thus, the mammals display the most significant complexity in the organic structure of animals, and represent the limit in the perfectioning and in the number of faculties which nature, with the help of this organic structure, was able to give to living bodies. Therefore, they must come at the end of the immense series of existing animals

Table of MammalsFIRST ORDER: EXUNGULATE MAMMALS

Only two limbs; they are in front, short, flattened, appropriate for swimming, and display neither nails nor hoofs.Cetaceans

Right-whaleRorqualPhysaleCachalotSperm-whale

NarwhalAnarnakDelphinopterusDolphinHyperodon

SECOND ORDER: AMPHIBIAN MAMMALSFour limbs; two short ones in front, as fins with unguiculate digits; the back two are directed towards the back or united with the extremity of the body, which is tail-like (as in fish)

SealWalrus

DugongManatee

ObservationThis order is placed here only because of the

relationship of the general form of the animals which make it up. See my observations on p. 143.

THIRD ORDER: UNGULATE MAMMALSFour limbs which are suitable only for moving; their digits are enclosed entirely at the ends by a horn which is called a hoof.

SolipedsHorseRuminants or Bisulcates

OxAntelopeGoatSheep

DeerGiraffeCamelMusk-deer

PachidermsRhinocerosHyraxTapir

PigElephantHippopotamus

FOURTH ORDER: UNGUICULATE MAMMALSFour limbs; flat or pointed nails at the end of their digits, which are not enclosed.TardigradesSlothEdentates

Ant-eaterPangolin

AardvarkArmadillo

RodentsKangarooHareCoenduPorcupineLemur

SpalaxSquirrelDormouseHamsterMarmot

PhascolomysHydromysBeaverCavy

VoleMusk-ratRat

PedimanaOpossumBandicootDasyurus

WombatCoescoesPhalanger

PlantigradesMoleShrewBearKinkajou

BadgerCoatiHedgehogTenrec

DigitgradesOtterMongooseSkunkWeasel

CatCivetHyaenaDog

ChiropteraGaleopithecusRhinolophusPhyllostome

NoctilioBatFlying-fox

QuadrumanesGalagoTarsius

BaboonSapajou

LorisMakiaIndrisGuenon

CebusAfrican-BaboonPongoOrang

Remark. According to the order which I have just presented, the family of quadrumanes is thus made up of the most perfect known animals, above all the last genera of this family. In effect, the genus Orang (pithecus) ends the entire order, just as the monad began it. What a difference with respect to organic structure and faculties between the animals of these two genera!

Naturalists who have considered man solely with respect to his organic structure have formed out of the six known varieties a particular genus, so that man alone makes up a separate family, characterized in the following way:

BIMANESMammals with separate limbs with nails; three types of teeth and opposable thumbs only on the handsMan

Varieties

CaucasianHyperboreanMongolianAmericanMalayanEthiopian or Negro

The name bimanes has been given to this family because, in effect, only human hands display a thumb separated and opposing the digits, while in the quadrumanes,

the hands and the feet show this same characteristic, so far as the thumb is concerned.

Some Observations Relevant to MenIf man were distinguished from animals only with

respect to his organic structure, it would be easy to show that the characteristics of organic structure which one would use to form a separate family (with its varieties) are all the products of ancient changes in his actions and habits which he acquired and what have become special to the individuals of his species.

In fact, if some race or other of quadrumanes, above all the most perfected among them, were to lose (by necessity of circumstance or some other cause) the habit of climbing up trees and grasping branches with their feet, as with their hands, to hang on there, and if the individuals of this race, over a succession of generations, were forced to use their feet only for movement and stopped using their hands as feet, there is no doubt, after the observations revealed in the preceding chapter, that these quadrumanes would finally be transformed into bimanes and that the thumbs on their feet would cease to be separated from the digits, since these feet serve them only for movement.

Moreover, if the individuals I am talking about, moved by the need to grow higher so as to see all at once far and wide, were forced to hold themselves upright and acquired from that a constant habit from one generation to the next, there is no doubt once again that their feet would have insensibly taken on a shape appropriate for holding them in an upright position, that their limbs would acquire calves, and

that these animals could only move around with difficulty on their hands and feet at the same time.

Finally, if these same individual were to stop using their jaws as weapons for biting, tearing, or seizing, or like pincers for cutting grass to eat, and if they were used only for chewing, once more there is no doubt that their facial angle would become more open, that their muzzle would shorten more and more, and would be finally effaced and they would have vertical incisor teeth.

Suppose now that a race of quadrumanes, like the most perfect, having acquired by constant habits in all its individuals the form which I have just referred to and the faculty of standing erect and walking upright and that later this race succeeded in dominating the other races of animals. In such a case one will see the following:

1. This race, more perfect in its capabilities, having because of these finally come to master the others, will spread itself out over the surface of the earth into all places which are suitable for it.2. This race will have chased off the other prominent races and, in the event of a dispute about what the good the earth offers, it would have forced them to take refuge in places which this race does not occupy.3. By harming the large multiplication of the races close to it in their affinities and having relegated them to the woods or other deserted places, this race will have stopped the progress in the perfection of their faculties; while that race itself, capable of extending itself everywhere, will multiply there without obstacles from the others and live there in numerous troops; it

will have successively created new needs which will stimulate its industry and gradually perfect its methods and capabilities.4. Finally, this preeminent race, having acquired an absolute supremacy over all the others, will have succeeded at putting between itself and the most perfect animals some difference and, in one way or another, a considerable distance.Thus, the race of the most perfect quadarumanes will

have been able to become dominant, to change its habits as a result of the absolute empire which it will have taken over the others and of new needs, and from that to acquire progressively modifications in its organic structure and numerous new capabilities, to restrict the most perfect of the other races to the state at which they have arrived; and to introduce very remarkable distinctions between itself and the latter.

The Orang of Angola (Simia troglodytes, Lin.) is the most perfect of animals: it is much more so than the orang of the Indies (Simia satyrus, Lin.), which has been called the orang-outang. Nevertheless, with respect to their organic structure, they are both far inferior to man in coporeal faculties and in intelligence11. These animals hold themselves upright on many occasions, but since they have not developed this into a sustained habit, their organic structure has not been sufficiently modified, so that standing up is a very inconvenient and uncomfortable condition for them.

11 See in my Recherches sur les Corps vivans, p. 136, some observations on the Orang of Angola.

We know (by accounts of travelers) above all in connection with the orang of the Indies, that when a pressing danger obliges them to run away, the animal immediately falls back onto its four limbs. According to us, that reveals the true origin of this animal, because it is forced to abandon this strange bearing which is foreign to it.

Without doubt this upright bearing is foreign to the animal, since it makes less use of it when it moves about . Hence its organic structure is less appropriate for such a stance. But because that stance is easier for man, is it entirely natural to him?

For man who, through the sustained habits of the individuals in his species over a long sequence of generations, can hold himself upright as he moves around, this stance is nonetheless a tiring state for him, a condition in which he is not able to sustain himself except for a limited time and with aid of the contractions of several of his muscles.

If the verbebral column of the human body were to form the axis of the body and to hold the head at equilibrium, as well as the other parts, man would be able to be in a state of repose while upright. Now, we all know that that is not the case, that the head does not move itself at the body's centre of gravity, that the chest and the stomach, as well as the viscera which these cavities enclose, weigh down almost totally on the front part of the vertebral column, that this column itself rests upon an oblique base, and so on. Thus, as Richerand observes, it is necessary that while man is standing, an active power constantly keep watch to prevent the falls which the

weight and the distribution of the parts always tend to encourage in the body.

After having developed the matters relevant to the stance of man, the same scholar explained himself as follows: "The relative weights of the head, the abdominal and thoracic viscera thus tend to pull forward that line, as a result of which all the parts of the body weigh on the plane which maintains it, a line which should be exactly perpendicular to this plane so that the stance is perfect. The following fact lends support to this assertion. I have observed that the children whose head is voluminous, the belly jutting forward, and the viscera overfull with fat accustom themselves to standing upright with difficulty. It is hardly at the end of their second year when they dare totrust their own powers. They remain subject to frequent falls and have a natural tendency to reassume the condition of a quadruped." Physiology, vol. II, p. 268.

This arrangement of parts which establishes the stance of man is an active state and thus tiring (rather than being a relaxed state). Hence, it would reveal in man an origin analogous to that of the other mammals, if his organic structure alone were taken into considerations.

Now, in order to follow, in all its points, the hypothesis presented from the start of these observations, it is appropriate to add the following considerations.

The individuals of the dominant race we are talking about spread out into all the habitable places suitable for them. Having considerably multiplied their needs as the societies which they formed became more numerous they would have had to by the same process multiply their ideas and thus to have felt the need to communicate with those like

them. We may imagine that from this resulted the necessity for them to increase and to vary to the same extent the signs appropriate for the communication of these ideas. Thus, it is evident that the individuals of this race would have had to make continual effort to create, multiply, and vary sufficiently the signs which their ideas and numerous needs rendered essential.

This is not the case with other animals. For although the most perfect among them, like the quadrumanes, live for the most part in groups, since the remarkable supremacy of the race we are talking about, they have remained without progressing in the perfectioning of their faculties, having been chased away everywhere and relegated to wilderness areas, deserts usually limited in extent, where, unhappy and restless, they are forced continuously to flee and hide. In this situation, these animals no longer form new needs, acquire new ideas. Their ideas remain few and do not change. And among these ideas there are very few which they would need to communicate to other individuals of the same species. Thus, they need only very few different signs to make themselves understood to those like them. Hence, some movements of the body or some of its parts, a few hissings and cries varied by simple vocal inflections are enough for them.

By contrast, the individuals of the dominant race already mentioned, having had a need to multiply the signs to communicate quickly their ideas (which have become more and more numerous), and not resting content with pantomime signs or the possible inflections of their voice, in order to represent this multitude of signs which has become necessary would have succeeded, by different efforts, in forming

articulated sounds. At first they would have used only a small number, combined with the inflections of their voice. Afterwards, they would have increased them, varied them, and perfected them, according to the growth of their needs and to the extent that they would have made more effort to produce them. In fact, the habitual exercise of the throat, tongue, and lips to articulate sounds would have really developed this faculty in them.

From that would come, for this particular race, the origin of the admirable capability of talking. And since the distance between places where the individuals making up this race would have widened and encouraged the corruption of the signs agreed upon in order to convey each idea, from that would have originated languages, which have been diversified everywhere.

Thus, in this matter, needs alone would have achieved everything. They would have given birth to efforts, and the organs appropriate to the articulation of sounds would have developed by their habitual use.

Such might be the reflections which one could make if man, considered here as the preeminent race in question, were not distinguished from animals except by the characteristics of his organic structure and if his origin were not different from theirs.

END OF THE FIRST PART