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The preserzution of natard bistory specimem Didogue between a ?mseoZogist, Geneviève Meurgaes, and a museum-user, Serge Cron, organizer of socio-educutìonaZ activities

Geneviève Meurgues

Born in Parris on 4 February 1931. Chemical engineer, distinction in biochemistry at the Conser- vatoire National des Arts et Métiers, graduate degree in Natural Sciences and Advanced Studies Diploma in Zoology. Head of the Department of Museological and Educational Research of the Na- tional Museological Service, National Museum of Natural History, Paris. Thesis for engineering diploma on 'The biosynthesis of nucleic acids in Aspergillus niger'.

Numerous publications on techniques developed in the laboratory for preserving natural history specimens (plants, molluscs. insects, etc.). popular science and scientific exhibitions. Member of the Association of Scientific Writers (France).

36 Fuchsia flower: facsimile model made by the Carnegie Museum (Pittsburg).

Cron: My visit to your museum with my pupils has left me very disappointed. I thought I would be able to use it as the starting point for an introduction to nature, and all we saw were shapeless, colourless plants and faded, dusty animals. It all seems very remote from nature, and anyone seeing such a sight may wonder whether, given the non-stop development of audio-visual techniques and opportunities to travel, natural science museums still serve a purpose nowadays.

Meurgues: Indeed they do, probably more than ever in our industrialized world, which is so long in information and so short in poetry. For a museum is not just a place in which to learn or ac- quire culture, it can also be somewhere to go for a few moment's respite from the cares of the day -somewhere where the mind can take flight and dream. A museum should be a place where the visitor can be enriched, not just culturally but intellectually and spiritually as well; and if the museologist has done his job properly the visitor should experience a kind of elation.

Crow Do you think that you can achieve your end by presenting us with a series of dusty, shapeless animal corpses that smell of moth-balls?

Neurgues: No, of course not. But old- fashioned displays of this kind date from a time when no distinction was drawn between a scientific collection, intended for research workers and a collection con- ceived for cultural and educational ends in view, that is to say for the public. In the first case, the main consideration is to en- sure that the information given on the specimen - origin, name of collector and date of collection-is accurate and that the specific characteristics necessary for systematic identification are preserv- ed. In addition, in order to identify species and sub-species it is essential to work, not on a single specimen, but on a series of individuals of the same species. This explains why old displays include veritable armies of animals of the same species - though it should not be forgot-

ten that the slaughter will have been spread over a period. The second type of collection is the kind intended for the public, and in this area spectacular efforts have been made in recent decades. Our task as museologists is to reveal nature in such a way that visitors will understand it and love it; and no museologist today is in any doubt that, if nature is to be loved, it must be presented as well as possible. Nature, of course, is life; it is also light, colour and movement; it is poetry and beauty. If we want to capture the visitor's attention, we must appeal to his sensibili- ty, and so we must look to the aesthetic side. The scientific message will only get across if the public are receptive, and we shall not achieve this by showing them fusty museums.

Cron. All this is fine in theory, but why are these principles not put into practice? I wonder whether the public might not be given a more effective introduction to nature if they were taken to a forest or a meadow in springtime.

Meurgues. You can be certain that the museologist - who is himself an educa- tor and, above all, a naturalist- has already asked himself this question. But this is where the specific problem of con- servation rears its head. The preservation of natural forms and colours is not a sim- ple matter. Take the case of plants. Here the curator and museologist are con- fronted with two major problems: the preservation of shapes and the preserva- tion of colour. In the oldest museums, plants were displayed in the form of a herbarium, of interest only to the pur- poseful visitor already attracted to botany. Nowadays the few botanical galleries to be found in the world display either actual plants preserved by freeze-drying, or else facsimile models. The Natural Science Museum, Ottawa is pursuing an interesting experiment with a botanical gallery of living specimens, but this type of display is expensive to maintain. American museums display completely lifelike artificial plants, and the only problem of preservation is the minor one of dust; they are often mould- ed in wax or plastic by volunteer helpers

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The preservation of nutural' histoq specimens 93

(Fig. 36). In Chinese museums, the plants are made of silk and bear a remarkable likeness to the original. For the preservation of real plants, the technique of lyophilization or freeze- drying is applied.' Fungi, some species of which contain up to per cent water, res- pond very well to freeze-drying and look completely lifelike. Flowering plants are more difficult to prepare because the chlorophyll normally concentrated in the chloroplasts migrates into the tissues, with the result that the specimen fades and has to be artificially retinted. The coloured pigments in flowers respond to dehydration in various ways according to their chemical composition (flavonic or anthocyanic; the yellow pigments withs- tand the process perfectly) and their distribution in the tissues. Once the specimen has been prepared in this way, the problem is how to preserve it over time. It must obviously be protected from damp and also from oxygen, which would oxidize the coloured pigments in a reaction catalysed by the ultraviolet rays. The solution is to preserve the mounted specimen in an oxygen-free medium, i.e. in an inert gas such as nitrogen or anhydrous argon.

Cr012. You have just referred to the harm- ful effects of ultraviolet rays. It seems to me that this is a general problem; there are hardly any coloured pigments that can withstand them indefinitely. Perhaps this explains the discoloration of the specimens that so disappointed us on our visit to your museum.

Meurgues. Indeed; and even the sunlight that the curator-naturalist needs so badly in order to live causes him a lot of anxiety. However, modern museology has made great strides, and certain aberrations - such as museums built completely win- dowless for fear of the sunlight - are on the way out. Glass that filters the ultraviolet out of the sunlight, is ob- tainable today. Museums are now being built that have windows made of this glass. It is also recommended practice to make display windows of it and to employ artificial light containing little or no ultraviolet radiation as secondary lighting. There are also anti-ultraviolet

1. The process consists in slow dehydration at low temperature in a vacuum. The specimen for dehydration is frozen so that all the liquids are solidified; it is then placed in a vacuum, whereupon the water is transformed from the solid to the gaseous state without passing through the liquid state, and thus without damage to the tissues.

37 Dioramas made by the National Museum of Natural History (New York): stuffed animals and artificial vegetation.

38 (4 , (b) Diorama made by the Field Museum (Chicago): stuffed animals in an entirely artificial habitat.

94 Geneviève Meurgues

39 varnishes which, when applied to the Diorama made by the Zoologisk M L W I ~ light source or to the glass panes, (Copenhagen): stuffed animals. Natural eliminate the harmful effects of this kind tree-trunks in the foreground against a painted backdrop. The leaves are artificial. Of radiation.

Cron. I am gradually beginning to realize the difficulties of preserving plants in a lifelike condition. But why is it that the animals always look so stiff and un- natural?

Meargues. With plants, although preser- vation is a complex problem, there is nevertheless some uniformity of physico- chemical structure. But this is not true of animals: there are basic differences be- tween a jellyfish and a large mammal! These differences relate to the skeleton -whether present or absent, internal or external; to the integuments - mem- brane, skin, shell, scales, fur or feathers; and to the chemical constitution of the

internal environment - the presence or absence of lipids. Each zoological group presents its own problems.

Insects, with their external skeleton, are fairly easy to preserve; they simply have to be dried following preparation. Their soft-skinned larvae are more dif- ficult to prepare, but freeze-dry well. If they are to be displayed to the public, they need only be dehydrated by these techniques. Larvae intended for scientific collections are kept in a preservative medium - 70 per cent ethyl alcohol or alcohol-acetic acid. Parasites are a scourge of insect collections, whatever their nature: museum-beetles, psocids, and micro-ants and mildews that develop in damp places. The recommended remedy in such cases is to use a pesticide such as lindane for either prevention or cure. The colours of insects, like those of plants, are damaged by ultraviolet rays. To protect them, it is sufficient to apply one of the methods suggested for the preservation of plant pigments.

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Cron. I am a keen skin-diver and it seems to me that the sea is where you find the most spectacular animal shapes and col- ours. Yet these animals are not to be found in museums.

Meurgues. Marine animals - sponges, hydroida, worms, jellyfish and molluscs -present museologists with what is without doubt their greatest problem. Traditionally such animals were kept in liquid preservatives, but the colours quickly fade and this method is now used only for scientific collections. Where the specimens are intended for public display and no satisfactory technique is available, we fall back on the facsimile model. For example, consider a soft-skinned jelly- fish: this animal can only keep its shape in a liquid medium and there is no such medium that will preserve the animal's colours. The only solution is to make a model in wax, glass or plastic.

Cron. I 'find that kind of display un- satisfactory, because I always wonder whether the execution is faithful. I would rather have a good photograph.

Meurgzles. Chinese museologists have developed a graphic technique which can provide a very good substitute for the real thing. They take a black-and-white photograph of the specimen concerned and paint in the colours on the negative in transparent varnish. Lit from behind, this image produces a three-dimensional

The preservation of natural' history specimens 95

impression and, although the colours are artificial, the photograph faithfully reproduces shapes.

Molluscs - animals whose biology is fascinating - are represented in mu- seums only by their shells because the soft part is difficult to preserve. However, there are ways of keeping the whole animal for display. The problem is to keep them fully extended until death; in other words, to keep the soft part outside the shell. This can be done by using bar- biturates, but the dose needed varies with the species, the age of the specimen and the muscles to be treated. A drug which in a given species acts upon the muscles of the siphons will have no effect on the pedal muscles and vice versa. Once the animal is dead in the fully extended state - which in the case of the shellfish means outside the shell with the in- teguments distended - the tissues can be dehydrated by freeze-drying. Thus treated, the animal can be displayed in its natural habitat: in the case of a filtering animal such as a cockle, the sand in which it usually lives, water being simulated in plastic. If the aim is to show the public how these animals feed, such a presenta- tion is essential.

Cron. I can see the difficulties you have in preserving invertebrates - animals with- out a skeletal structure; but why is it that vertebrates - often the animals most fascinating to the public because of their size and because they are more familiar to us - are so often mere caricatures.

Meurgues. Perhaps because here, even more than in the cases we have been discussing, artistic talent is the deciding factor. Mammals and birds are prepared by taxidermists, who are naturalists, technicians and at the same time artists specializing in animals. The technique of preparing mammals and birds begins at the animal's death, with taking its measurements, noting any colours liable to fade (eyes, mucous membranes) and cutting up the body, while noting all anatomical features relating to the skeleton, the positioning of the muscles and their relief. The skin is treated separately by tanning in alum; in small animals, parts of the skeleton such as the skull or leg bones may remain attached. With small or medium-sized animals up to the size of a German shepherd dog, a wire framework is used to reconstruct the shape of the animal. This is then covered by the skin and stuffed full of tow and wood fibre. This operation is followed by

modelling, and here the taxidermist must use all his talent in order to give a dead animal the appearance of life (Figs. 37,40). With larger animals, the techni- que is to use mannequins made of wire mesh and plaster. The skin is stuffed as before. Some taxidermists construct, on the basis of an anatomical model, a thin shell of fibreglass and plastic to serve as a mannequin. Such a shell, being less susceptible to variations in temperature and humidity than other materials, is more durable. When they are intended to serve scientific purposes, mammals and birds are treated differently. The technique employed is to stuff the skin with tow, without attempting to restore the real shape of the animal. Certain parts of the skeleton vital to the iden- tification of the specimen are retained within the skin. Such animals can also be kept in a liquid preservative (alcohol or formalin); this is the usual procedure with anatomical collections. As with in- sects (Fig. 41), mildew will develop on skins and feathers if the ambient humidi- ty and temperature are too high. On the other hand, if the ambient air is too dry, cracks will appear. Certain insects - museum beetles and dermestids - may also infest feathers and skins; whole col- lections have been decimated in this way. It is therefore recommended that mam- mal and bird collections should be kept at a temperature of not more than 18-20 "C and relative humidity of 70 O , and be pro- tected from parasites by periodic treat- ment with pesticides (naphthaline or lindane).

Cron. So much for the characteristic smell that haunts the galleries of natural science museums! Why is it that in- teresting animals such as fish are so often displayed in jars?

Meurgues. Because fish, like reptiles and amphibians, are not easy to preserve for museological purposes. The most wide- spread method of preserving these three categories of animals is to use a liquid preservative (alcohol or formalin). Cer- tain kinds of fish were preserved in her- baria. Nowadays this form of preserva- tion is used mainly for scientific collections; the coloured pigments are destroyed by the preservative fluids but the anatomical characteristics are main- tained intact. It is also possible to preserve reptiles in a bath of liquid paraf- fin, though this presents some draw- backs. Other preserving media based on osmic acid have been developed, but they

40 Close-up of the leaves in the Copenhagen diorama.

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96 Geneviève Meurgues

41 Facsimile of a fly made by the British Museum (Natural History), London.

proved to be very expensive and toxic, and have been abandoned. As with mammals and birds, it is possible to preserve reptiles, amphibians and fish by dehydrating them in successive baths of increasingly concentrated ethyl alcohol and giving them a final treatment with terpineol to restore their suppleness and shine. Unfortunately this method does not fix coloured pigments, and within one or two years the natural colours fade. It is therefore desirable to colour the specimens artificially. The freeze-drying technique can be used successfully on fish, once they have been prepared, but here again the colours fade and it is necessary to retint (Figs. 42-44). Fac- similes in wax or in resin and wax give satisfactory results where shape is con- cerned but are disappointing in colour. The Chinese technique of painting a film negative with transparent paints is par- ticularly effective with fish.

Cron. I have another complaint to make: not being allowed to touch the objects displayed in your museums. I understand from your explanations how valuable all the specimens are, but I should like to be able to stroke an animal.

Meurgues. We are well aware of this problem, and there are museums where animals such as mammals and birds are accessible, in particular to children. The public is very keen on the kind of display that recreates nature, known as a diorama. When a specimen of any kind has been mounted, we can display it either in a systematic arrangement or in a diorama, that is to say in its ecological set- ting. It is of great educational value to recreate the ecosystem in which the specimen developed, because it gives the visitor an idea of what things are really like. But a diorama is the most difficult thing of all to make, first and foremost because, like any other kind of museum display, it needs to be done well. Being taken from life, it must not betray nature, and scientific accuracy is essen- tial; for example, it is unthinkable that an orchid which grows in chalky soil should ever be shown in a diorama where the substrate was siliceous!

Cron. Well then, supposing you want to recreate a forest or at least a fragment of one, how do you set about freeze-drying a tree?

Meurgzles. The preservation of large-scale plants in their natural state is not feasible

with current techniques, and so the museologist has recourse to the artificial. The dioramas on show in the big American museums are made up of en- tirely artificial vegetation - trees, plants and flowers -using the technique I described to you a moment ago. One very important factor is lighting. A balance has to be struck between the lighting in the room and the display lighting, which must be effective but not dazzling. The lighting is often the charm of a diorama. It is also possible to create an illusion of water by using blue lighting, for example in displays of marine animals.

Live animals have their educational value too, but this would not be enough. It is impossible to acclimatize all species in a zoo. As a rule, most of the animals displayed belong to species which have been domesticated in their countries of origin, and this is a limiting factor. Animals such as bears and the great apes are tending to disappear from zoos, because they suffer in captivity.

A display of live animals is essential to convey some elements of biology, behaviour, biological rhythms and any other attribute that is difficult to explain with dead specimens. In large cities, the ‘children’s farm’, which brings the coun- try to the town in the shape of domestic livestock, is proving very popular with youngsters, who have a chance to watch the gestation, birth and development of young animals. But this is not enough, and a museum needs to exhibit at several levels in order to cater for different groups of users.

Cron. Would it be true to say that the most important role of the natural science museum is to educate? What other func- tions do museums perform?

Meurgues. Many. A museum is perhaps first and foremost a storehouse, for without its collections, which must be maintained and enriched, it would have no real purpose. A museum curator is also a ‘field worker’, who can only do his or her job properly to the extent that he or she is familiar with nature through repeated contact with it. To com- municate with the public, he or she needs to be a keen naturalist; in my view, no one can be a museologist unless he or she is an enthusiast with a positive passion for the work.

As we have been saying all along, a natural science museum is also a cultural centre, and the events staged for the various categories of users may include

The preservation of naturd hihory specimens 97

permanent or temporary exhibitions, talks and guided tours of the various displays. If the museum is to come alive, it is vital that such events should be laid on, and this is where the activities organizer comes into his own,

Building up a natural science museum is an extremely difficult task - almost a gamble. To return to the theme of our discussion, namely the preservation of natural specimens, the museologist is confronted by another problem - a problem of conscience. Many of us have upheld the principle that natural science museums should display only natural specimens - former living organisms - on the ground that these are more ‘real’ to the public. But besides museologists we are also naturalists, and this means that we sometimes hesitate to sacrifice an animal or a plant. Moreover, although technology has made great advances in our field, it does not always provide us with the technique to preserve a specimen; hence our recourse to the fac- simile model. The question that many of us are asking is whether we should be doggedly striving to develop conservation techniques for natural botanical or zoological specimens or whether we

42 Freeze-dried salmon, Musée National d’Histoire Naturelle (Paris).

should be trying to imitate nature as perfectly as possible by artificial means. 43

Close-up of the salmon’s scales. ,

Cron. Perhaps that is one for the public to answer.

[ Trundatedfrom French]

1 ; ,

44 Freeze-dried mollusc, Musée National d’Histoire Naturelle (Paris). Displayed in its reconstituted habitat.