lectures and essays by huxley, thomas henry, 1825-1895

8/14/2019 Lectures and Essays by Huxley, Thomas Henry, 1825-1895

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Title:LecturesandEssays

Author:T.H.Huxley

ReleaseDate:September,2004[EBook#6414][Yes,wearemorethanoneyearaheadofschedule][ThisfilewasfirstpostedonDecember8,2002]

Edition:10

Language:English

Charactersetencoding:ASCII

***STARTOFTHEPROJECTGUTENBERGEBOOKLECTURESANDESSAYS***

[email protected]

LecturesandEssays

byT.H.Huxley

***

THEPEOPLE'SLIBRARY.


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LECTURESANDESSAYS.

THOMASHENRYHUXLEY.

EDITOR'SNOTE.

Ofthegreatthinkersofthenineteenthcentury,ThomasHenryHuxley,sonofanEalingschoolmaster,wasundoubtedlythemostnoteworthy.Hisresearchesinbiology,hiscontributionstoscientificcontroversy,hispungentcriticismsofconventionalbeliefsandthoughtshaveprobablyhadgreaterinfluencethantheworkofanyotherEnglishscientist.Andyethewasa"self-made"intellectualist.Inspiteofthefactthathisfatherwasaschoolmasterhepassedthroughnoregularcourseofeducation."Ihad,"hesaid,"twoyearsofapandemoniumofaschool(betweeneightandten)andafterthatneitherhelpnorsympathyinany

intellectualdirectiontillIreachedmanhood."WhenhewastwelveacravingforreadingfoundsatisfactioninHutton's"Geology,"andwhenfifteeninHamilton's"Logic."

AtseventeenHuxleyenteredasastudentatCharingCrossHospital,andthreeyearslaterhewasM.B.andthepossessorofthegoldmedalforanatomyandphysiology.AnappointmentassurgeoninthenavyprovedtobetheentrytoHuxley'sgreatscientificcareer,forhewasgazettedtothe"Rattlesnake",commissionedforsurveyingworkinTorresStraits.Hewasattractedbytheteemingsurfacelifeoftropicalseasandhisstudyofitwasthecommencementofthatrevolutioninscientificknowledgeultimatelybroughtaboutbyhisresearches.

ThomasHenryHuxleywasbornatEalingonMay4,1825,anddiedatEastbourneJune29,1895.

***

LECTURES

AND

ESSAYS

BY

T.H.HUXLEY.

CASSELLANDCOMPANY,LTD.LONDON,PARIS,NEWYORK,TORONTO&MELBOURNE.MCMVIII.


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***

CONTENTS.

ONOURKNOWLEDGEOFTHECAUSESOFTHEPHENOMENAOFORGANICNATURE:

THEPRESENTCONDITIONOFORGANICNATURE.

THEPASTCONDITIONOFORGANICNATURE.

THEMETHODBYWHICHTHECAUSESOFTHEPRESENTANDPASTCONDITIONSOFORGANICNATUREARETOBEDISCOVERED.--THEORIGINATIONOFLIVINGBEINGS.

THEPERPETUATIONOFLIVINGBEINGS,HEREDITARYTRANSMISSIONANDVARIATION.

THECONDITIONSOFEXISTENCEASAFFECTINGTHEPERPETUATIONOFLIVINGBEINGS.

ACRITICALEXAMINATIONOFTHEPOSITIONOFMR.DARWIN'SWORK,"ONTHE

ORIGINOFSPECIES,"INRELATIONTOTHECOMPLETETHEORYOFTHECAUSESOFTHEPHENOMENAOFORGANICNATURE.

ESSAYSONDARWIN'S"ORIGINOFSPECIES":

THEDARWINIANHYPOTHESIS.

TIMEANDLIFE.

THEORIGINOFSPECIES.

CRITICISMSON"THEORIGINOFSPECIES".

EVIDENCEASTOMAN'SPLACEINNATURE:

ONTHENATURALHISTORYOFTHEMAN-LIKEAPES.

ONTHERELATIONSOFMANTOTHELOWERANIMALS.

ONSOMEFOSSILREMAINSOFMAN.

ONTHEADVISABLENESSOFIMPROVINGNATURALKNOWLEDGE.

ONTHESTUDYOFZOOLOGY.

GEOLOGICALCONTEMPORANEITYANDPERSISTENTTYPESOFLIFE.

CORALANDCORALREEFS.


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YEAST.

THECIRCULATIONOFTHEBLOOD.

***

ONOURKNOWLEDGE

OFTHECAUSESOFTHEPHENOMENA

OF

ORGANICNATURE.

NOTICETOTHEFIRSTEDITION.

ThePublisheroftheseinterestingLectures,havingmadeanarrangementfortheirpublicationwithMr.J.A.Mays,theReporter,begstoappend

thefollowingnotefromProfessorHuxley:--

"Mr.J.AldousMays,whoistakingshorthandnotesofmy'LecturestoWorkingMen,'hasaskedmetoallowhim,onhisownaccount,toprintthoseNotesfortheuseofmyaudience.Iwillinglyaccedetothisrequest,ontheunderstandingthatanoticeisprefixedtotheeffectthatIhavenoleisuretorevisetheLectures,ortomakealterationsinthem,beyondthecorrectionofanyimportanterrorinamatteroffact."

***

ONOURKNOWLEDGEOFTHECAUSESOFTHEPHENOMENAOFORGANICNATURE:

THEPRESENTCONDITIONOFORGANICNATURE.

WhenitwasmydutytoconsiderwhatsubjectIwouldselectforthesixlectures*([Footnote]*ToWorkingMen,attheMuseumofPracticalGeology,1863.)whichIshallnowhavethepleasureofdeliveringtoyou,itoccurredtomethatIcouldnotdobetterthanendeavourtoputbeforeyouinatruelight,orinwhatImightperhapswithmoremodestycall,thatwhichIconceivemyselftobethetruelight,thepositionofabookwhichhasbeenmorepraisedandmoreabused,perhaps,thananybookwhichhasappearedforsomeyears;--ImeanMr.Darwin'sworkonthe"OriginofSpecies".Thatwork,Idoubtnot,manyofyouhaveread;for

Iknowtheinquiringspiritwhichisrifeamongyou.Atanyrate,allofyouwillhaveheardofit,--somebyonekindofreportandsomebyanotherkindofreport;theattentionofallandthecuriosityofallhavebeenprobablymoreorlessexcitedonthesubjectofthatwork.AllIcando,andallIshallattempttodo,istoputbeforeyouthatkindofjudgmentwhichhasbeenformedbyaman,who,ofcourse,isliabletojudgeerroneously;but,atanyrate,ofonewhosebusinessandprofessionitistoformjudgmentsuponquestionsofthisnature.

Andhere,asitwillalwayshappenwhendealingwithanextensive


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subject,thegreaterpartofmycourse--if,indeed,sosmallanumberoflecturescanbeproperlycalledacourse--mustbedevotedtopreliminarymatters,orrathertoastatementofthosefactsandofthoseprincipleswhichtheworkitselfdwellsupon,andbringsmoreorlessdirectlybeforeus.Ihavenorighttosupposethatalloranyofyouarenaturalists;andevenifyouwere,themisconceptionsandmisunderstandingsprevalentevenamongnaturalistsonthesematterswouldmakeitdesirablethatIshouldtakethecourseInowproposetotake,--thatIshouldstartfromthebeginning,--thatIshouldendeavourtopointoutwhatistheexistingstateoftheorganicworld,--thatIshouldpointoutitspastcondition,--thatIshouldstatewhatistheprecisenatureoftheundertakingwhichMr.Darwinhastakeninhand;thatIshouldendeavourtoshowyouwhataretheonlymethodsbywhichthatundertakingcanbebroughttoanissue,andtopointouttoyouhowfartheauthoroftheworkinquestionhassatisfiedthoseconditions,howfarhehasnotsatisfiedthem,howfartheyaresatisfiablebyman,andhowfartheyarenotsatisfiablebyman.

To-night,intakingupthefirstpartofthisquestion,Ishallendeavourtoputbeforeyouasortofbroadnotionofourknowledgeoftheconditionofthelivingworld.Therearemanywaysofdoingthis.Imightdealwithitpictoriallyandgraphically.FollowingtheexampleofHumboldtinhis"AspectsofNature",Imightendeavourtopointouttheinfinitevarietyoforganiclifeineverymodeofitsexistence,with

referencetothevariationsofclimateandthelike;andsuchanattemptwouldbefraughtwithinteresttousall;butconsideringthesubjectbeforeus,suchacoursewouldnotbethatbestcalculatedtoassistus.Inanargumentofthiskindwemustgofurtheranddigdeeperintothematter;wemustendeavourtolookintothefoundationsoflivingNature,ifImaysosay,anddiscovertheprinciplesinvolvedinsomeofhermostsecretoperations.Ipropose,therefore,inthefirstplace,totakesomeordinaryanimalwithwhichyouareallfamiliar,and,byeasilycomprehensibleandobviousexamplesdrawnfromit,toshowwhatarethekindofproblemswhichlivingbeingsingenerallaybeforeus;andIshallthenshowyouthatthesameproblemsarelaidopentousbyallkindsoflivingbeings.Butfirst,letmesayinwhatsenseIhaveusedthewords"organicnature."Inspeakingofthecauseswhichleadto

ourpresentknowledgeoforganicnature,Ihaveuseditalmostasanequivalentoftheword"living,"andforthisreason,--thatinalmostalllivingbeingsyoucandistinguishseveraldistinctportionssetaparttodoparticularthingsandworkinaparticularway.Thesearetermed"organs,"andthewholetogetheriscalled"organic."Andasitisuniversallycharacteristicofthem,thisterm"organic"hasbeenveryconvenientlyemployedtodenotethewholeoflivingnature,--thewholeoftheplantworld,andthewholeoftheanimalworld.

Fewanimalscanbemorefamiliartoyouthanthatwhoseskeletonisshownonourdiagram.Youneednotbotheryourselveswiththis"Equuscaballus"writtenunderit;thatisonlytheLatinnameofit,anddoesnotmakeitanybetter.ItsimplymeansthecommonHorse.Supposewe

wishtounderstandallabouttheHorse.Ourfirstobjectmustbetostudythestructureoftheanimal.Thewholeofhisbodyisinclosedwithinahide,askincoveredwithhair;andifthathideorskinbetakenoff,wefindagreatmassofflesh,orwhatistechnicallycalledmuscle,beingthesubstancewhichbyitspowerofcontractionenablestheanimaltomove.Thesemusclesmovethehardpartsoneupontheother,andsogivethatstrengthandpowerofmotionwhichrenderstheHorsesousefultousintheperformanceofthoseservicesinwhichweemployhim.


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Andthen,onseparatingandremovingthewholeofthisskinandflesh,youhaveagreatseriesofbones,hardstructures,boundtogetherwithligaments,andformingtheskeletonwhichisrepresentedhere.

(FIGURE1.Sectionthroughahorse.

FIGURE2.Sectionthroughacell.)

Inthatskeletonthereareanumberofpartstoberecognized.Thelongseriesofbones,beginningfromtheskullandendinginthetail,iscalledthespine,andthoseinfrontaretheribs;andthentherearetwopairsoflimbs,onebeforeandonebehind;andtherearewhatweallknowasthefore-legsandthehind-legs.Ifwepursueourresearchesintotheinteriorofthisanimal,wefindwithintheframeworkoftheskeletonagreatcavity,orrather,Ishouldsay,twogreatcavities,--onecavitybeginningintheskullandrunningthroughtheneck-bones,alongthespine,andendinginthetail,containingthebrainandthespinalmarrow,whichareextremelyimportantorgans.Thesecondgreatcavity,commencingwiththemouth,containsthegullet,thestomach,thelongintestine,andalltherestofthoseinternalapparatuswhichareessentialfordigestion;andtheninthesamegreatcavity,therearelodgedtheheartandallthegreatvesselsgoingfromit;and,besidesthat,theorgansofrespiration--thelungs:andthenthekidneys,andtheorgansofreproduction,andsoon.Letusnow

endeavourtoreducethisnotionofahorsethatwenowhave,tosomesuchkindofsimpleexpressionascanbeatonce,andwithoutdifficulty,retainedinthemind,apartfromallminordetails.IfImakeatransversesection,thatis,ifIweretosawadeadhorseacross,Ishouldfindthat,ifIleftoutthedetails,andsupposingItookmysectionthroughtheanteriorregion,andthroughthefore-limbs,Ishouldhaveherethiskindofsectionofthebody(Figure1).Herewouldbetheupperpartoftheanimal--thatgreatmassofbonesthatwespokeofasthespine(a,Figure1).HereIshouldhavethealimentarycanal(b,Figure1).HereIshouldhavetheheart(c,Figure1);andthenyousee,therewouldbeakindofdoubletube,thewholebeinginclosedwithinthehide;thespinalmarrowwouldbeplacedintheuppertube(a,Figure1),andinthelowertube(dd,Figure1),therewould

bethealimentarycanal(b),andtheheart(c);andhereIshallhavethelegsproceedingfromeachside.Forsimplicity'ssake,Irepresentthemmerelyasstumps(ee,Figure1).Nowthatisahorse--asmathematicianswouldsay--reducedtoitsmostsimpleexpression.Carrythatinyourminds,ifyouplease,asasimplifiedideaofthestructureoftheHorse.TheconsiderationswhichIhavenowputbeforeyoubelongtowhatwetechnicallycallthe'Anatomy'oftheHorse.Now,supposewegotoworkupontheseseveralparts,--fleshandhair,andskinandbone,--andlayopenthesevariousorganswithourscalpels,andexaminethembymeansofourmagnifying-glasses,andseewhatwecanmakeofthem.Weshallfindthatthefleshismadeupofbundlesofstrongfibres.Thebrainandnerves,too,weshallfind,aremadeupoffibres,andthesequeer-lookingthingsthatarecalledganglioniccorpuscles.If

wetakeasliceoftheboneandexamineit,weshallfindthatitisverylikethisdiagramofasectionoftheboneofanostrich,thoughdiffering,ofcourse,insomedetails;andifwetakeanypartwhatsoeverofthetissue,andexamineit,weshallfinditallhasaminutestructure,visibleonlyunderthemicroscope.Allthesepartsconstitutemicroscopicanatomyor'Histology.'Thesepartsareconstantlybeingchanged;everypartisconstantlygrowing,decaying,andbeingreplacedduringthelifeoftheanimal.Thetissueisconstantlyreplacedbynewmaterial;andifyougobacktotheyoungstateofthetissueinthecaseofmuscle,orinthecaseofskin,or


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anyoftheorgansIhavementioned,youwillfindthattheyallcomeunderthesamecondition.Everyoneofthesemicroscopicfilamentsandfibres(Inowspeakmerelyofthegeneralcharacterofthewholeprocess)--everyoneoftheseparts--couldbetraceddowntosomemodificationofatissuewhichcanbereadilydividedintolittleparticlesoffleshymatter,ofthatsubstancewhichiscomposedofthechemicalelements,carbon,hydrogen,oxygen,andnitrogen,havingsuchashapeasthis(Figure2).Theseparticles,intowhichallprimitivetissuesbreakup,arecalledcells.IfIweretomakeasectionofapieceoftheskinofmyhand,Ishouldfindthatitwasmadeupofthesecells.IfIexaminethefibreswhichformthevariousorgansofalllivinganimals,Ishouldfindthatallofthem,atonetimeorother,hadbeenformedoutofasubstanceconsistingofsimilarelements;sothatyousee,justaswereducedthewholebodyinthegrosstothatsortofsimpleexpressiongiveninFigure1,sowemayreducethewholeofthemicroscopicstructuralelementstoaformofevengreatersimplicity;justastheplanofthewholebodymaybesorepresentedinasense(Figure1),sotheprimarystructureofeverytissuemayberepresentedbyamassofcells(Figure2).

Havingthus,inthissortofgeneralway,sketchedtoyouwhatImaycall,perhaps,thearchitectureofthebodyoftheHorse(whatwetermtechnicallyitsMorphology),Imustnowturntoanotheraspect.Ahorseisnotameredeadstructure:itisanactive,living,workingmachine.

Hithertowehave,asitwere,beenlookingatasteam-enginewiththefiresout,andnothingintheboiler;butthebodyofthelivinganimalisabeautifully-formedactivemachine,andeveryparthasitsdifferentworktodointheworkingofthatmachine,whichiswhatwecallitslife.TheHorse,ifyouseehimafterhisday'sworkisdone,iscroppingthegrassinthefields,asitmaybe,ormunchingtheoatsinhisstable.Whatishedoing?Hisjawsareworkingasamill--andaverycomplexmilltoo--grindingthecorn,orcrushingthegrasstoapulp.Assoonasthatoperationhastakenplace,thefoodispasseddowntothestomach,andthereitismixedwiththechemicalfluidcalledthegastricjuice,asubstancewhichhasthepeculiarpropertyofmakingsolubleanddissolvingoutthenutritiousmatterinthegrass,andleavingbehindthosepartswhicharenotnutritious;sothatyouhave,

first,themill,thenasortofchemicaldigester;andthenthefood,thuspartiallydissolved,iscarriedbackbythemuscularcontractionsoftheintestinesintothehinderpartsofthebody,whilethesolubleportionsaretakenupintotheblood.Thebloodiscontainedinavastsystemofpipes,spreadingthroughthewholebody,connectedwithaforcepump,--theheart,--which,byitspositionandbythecontractionsofitsvalves,keepsthebloodconstantlycirculatinginonedirection,neverallowingittorest;andthen,bymeansofthiscirculationoftheblood,ladenasitiswiththeproductsofdigestion,theskin,theflesh,thehair,andeveryotherpartofthebody,drawsfromitthatwhichitwants,andeveryoneoftheseorgansderivesthosematerialswhicharenecessarytoenableittodoitswork.

Theactionofeachoftheseorgans,theperformanceofeachofthesevariousduties,involveintheiroperationacontinualabsorptionofthemattersnecessaryfortheirsupport,fromtheblood,andaconstantformationofwasteproducts,whicharereturnedtotheblood,andconveyedbyittothelungsandthekidneys,whichareorgansthathaveallottedtothemtheofficeofextracting,separating,andgettingridofthesewasteproducts;andthusthegeneralnourishment,labour,andrepairofthewholemachineiskeptupwithorderandregularity.Butnotonlyisitamachinewhichfeedsandappropriatestoitsownsupportthenourishmentnecessarytoitsexistence--itisanenginefor


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locomotivepurposes.TheHorsedesirestogofromoneplacetoanother;andtoenableittodothis,ithasthosestrongcontractilebundlesofmusclesattachedtothebonesofitslimbs,whichareputinmotionbymeansofasortoftelegraphicapparatusformedbythebrainandthegreatspinalcordrunningthroughthespineorbackbone;andtothisspinalcordareattachedanumberoffibrestermednerves,whichproceedtoallpartsofthestructure.Bymeansofthesetheeyes,nose,tongue,andskin--alltheorgansofperception--transmitimpressionsorsensationstothebrain,whichactsasasortofgreatcentraltelegraph-office,receivingimpressionsandsendingmessagestoallpartsofthebody,andputtinginmotionthemusclesnecessarytoaccomplishanymovementthatmaybedesired.Sothatyouhavehereanextremelycomplexandbeautifully-proportionedmachine,withallitspartsworkingharmoniouslytogethertowardsonecommonobject--thepreservationofthelifeoftheanimal.

Now,notethis:theHorsemakesupitswastebyfeeding,anditsfoodisgrassoroats,orperhapsothervegetableproducts;therefore,inthelongrun,thesourceofallthiscomplexmachineryliesinthevegetablekingdom.Butwheredoesthegrass,ortheoat,oranyotherplant,obtainthisnourishingfood-producingmaterial?Atfirstitisalittleseed,whichsoonbeginstodrawintoitselffromtheearthandthesurroundingairmatterswhichinthemselvescontainnovitalpropertieswhatever;itabsorbsintoitsownsubstancewater,aninorganicbody;it

drawsintoitssubstancecarbonicacid,aninorganicmatter;andammonia,anotherinorganicmatter,foundintheair;andthen,bysomewonderfulchemicalprocess,thedetailsofwhichchemistsdonotyetunderstand,thoughtheyarenearforeshadowingthem,itcombinesthemintoonesubstance,whichisknowntousas'Protein,'acomplexcompoundofcarbon,hydrogen,oxygen,andnitrogen,whichalonepossessesthepropertyofmanifestingvitalityandofpermanentlysupportinganimallife.Sothat,yousee,thewasteproductsoftheanimaleconomy,theeffetematerialswhicharecontinuallybeingthrownoffbyalllivingbeings,intheformoforganicmatters,areconstantlyreplacedbysuppliesofthenecessaryrepairingandrebuildingmaterialsdrawnfromtheplants,whichintheirturnmanufacturethem,sotospeak,byamysteriouscombinationofthosesameinorganicmaterials.

LetustraceoutthehistoryoftheHorseinanotherdirection.Afteracertaintime,astheresultofsicknessordisease,theeffectofaccident,ortheconsequenceofoldage,soonerorlater,theanimaldies.Themultitudinousoperationsofthisbeautifulmechanismflagintheirperformance,theHorselosesitsvigour,andafterpassingthroughthecuriousseriesofchangescomprisedinitsformationandpreservation,itfinallydecays,andendsitslifebygoingbackintothatinorganicworldfromwhichallbutaninappreciablefractionofitssubstancewasderived.Itsbonesbecomemerecarbonateandphosphateoflime;thematterofitsflesh,andofitsotherparts,becomes,inthelongrun,convertedintocarbonicacid,intowater,andintoammonia.Youwillnow,perhaps,understandthecuriousrelationoftheanimal

withtheplant,oftheorganicwiththeinorganicworld,whichisshowninthisdiagram(Figure3).

(FIGURE3.DiagramshowingmaterialrelationshipoftheVegetable,AnimalandInorganicWorlds.)

Theplantgatherstheseinorganicmaterialstogetherandmakesthemupintoitsownsubstance.Theanimaleatstheplantandappropriatesthenutritiousportionstoitsownsustenance,rejectsandgetsridoftheuselessmatters;and,finally,theanimalitselfdies,anditswhole


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bodyisdecomposedandreturnedintotheinorganicworld.Thereisthusaconstantcirculationfromonetotheother,acontinualformationoforganiclifefrominorganicmatters,andasconstantareturnofthematteroflivingbodiestotheinorganicworld;sothatthematerialsofwhichourbodiesarecomposedarelargely,inallprobability,thesubstanceswhichconstitutedthematteroflongextinctcreations,butwhichhaveintheintervalconstitutedapartoftheinorganicworld.

Thuswecometotheconclusion,strangeatfirstsight,thattheMATTERconstitutingthelivingworldisidenticalwiththatwhichformstheinorganicworld.Andnotlesstrueisitthat,remarkableasarethepowersor,inotherwords,asaretheFORCESwhichareexertedbylivingbeings,yetalltheseforcesareeitheridenticalwiththosewhichexistintheinorganicworld,ortheyareconvertibleintothem;Imeaninjustthesamesenseastheresearchesofphysicalphilosophershaveshownthatheatisconvertibleintoelectricity,thatelectricityisconvertibleintomagnetism,magnetismintomechanicalforceorchemicalforce,andanyoneofthemwiththeother,eachbeingmeasurableintermsoftheother,--evenso,Isay,thatgreatlawisapplicabletothelivingworld.Considerwhyistheskeletonofthishorsecapableofsupportingthemassesoffleshandthevariousorgansformingthelivingbody,unlessitisbecauseoftheactionofthesameforcesofcohesionwhichcombinestogethertheparticlesofmattercomposingthispieceofchalk?Whatisthereinthemuscularcontractilepoweroftheanimalbut

theforcewhichisexpressible,andwhichisinacertainsenseconvertible,intotheforceofgravitywhichitovercomes?Or,ifyougotomorehiddenprocesses,inwhatdoestheprocessofdigestiondifferfromthoseprocesseswhicharecarriedoninthelaboratoryofthechemist?Evenifwetakethemostreconditeandmostcomplexoperationsofanimallife--thoseofthenervoussystem,theseoflateyearshavebeenshowntobe--Idonotsayidenticalinanysensewiththeelectricalprocesses--butthishasbeenshown,thattheyareinsomewayorotherassociatedwiththem;thatistosay,thateveryamountofnervousactionisaccompaniedbyacertainamountofelectricaldisturbanceintheparticlesofthenervesinwhichthatnervousactioniscarriedon.Inthiswaythenervousactionisrelatedtoelectricityinthesamewaythatheatisrelatedtoelectricity;andthesamesort

ofargumentwhichdemonstratesthetwolattertoberelatedtooneanothershowsthatthenervousforcesarecorrelatedtoelectricity;fortheexperimentsofM.DuboisReymondandothershaveshownthatwheneveranerveisinastateofexcitement,sendingamessagetothemusclesorconveyinganimpressiontothebrain,thereisadisturbanceoftheelectricalconditionofthatnervewhichdoesnotexistatothertimes;andthereareanumberofotherfactsandphenomenaofthatsort;sothatwecometothebroadconclusionthatnotonlyastolivingmatteritself,butastotheforcesthatmatterexerts,thereisacloserelationshipbetweentheorganicandtheinorganicworld--thedifferencebetweenthemarisingfromthediversecombinationanddispositionofidenticalforces,andnotfromanyprimarydiversity,sofaraswecansee.

IsaidjustnowthattheHorseeventuallydiedandbecameconvertedintothesameinorganicsubstancesfromwhenceallbutaninappreciablefractionofitssubstancedemonstrablyoriginated,sothattheactualwanderingsofmatterareasremarkableasthetransmigrationsofthesoulfabledbyIndiantradition.Butbeforedeathhasoccurred,intheonesexortheother,andinfactinboth,certainproductsorpartsoftheorganismhavebeensetfree,certainpartsoftheorganismsofthetwosexeshavecomeintocontactwithoneanother,andfromthatconjunction,fromthatunionwhichthentakesplace,thereresultsthe


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formationofanewbeing.Atstatedtimesthemare,fromaparticularpartoftheinteriorofherbody,calledtheovary,getsridofaminuteparticleofmattercomparableinallessentialrespectswiththatwhichwecalledacellalittlewhilesince,whichcellcontainsakindofnucleusinitscentre,surroundedbyaclearspaceandbyaviscidmassofproteinsubstance(Figure2);andthoughitisdifferentinappearancefromtheeggswhichwearemostlyacquaintedwith,itisreallyanegg.Afteratimethisminuteparticleofmatter,whichmayonlybeasmallfractionofagraininweight,undergoesaseriesofchanges,--wonderful,complexchanges.Finally,uponitssurfacethereisfashionedalittleelevation,whichafterwardsbecomesdividedandmarkedbyagroove.Thelateralboundariesofthegrooveextendupwardsanddownwards,andatlengthgiverisetoadoubletube.Intheuppersmallertubethespinalmarrowandbrainarefashioned;inthelower,thealimentarycanalandheart;andatlengthtwopairsofbudsshootoutatthesidesofthebody,whicharetherudimentsofthelimbs.Infactatruedrawingofasectionoftheembryointhisstatewouldinallessentialrespectsresemblethatdiagramofahorsereducedtoitssimplestexpression,whichIfirstplacedbeforeyou(Figure1).

Slowlyandgraduallythesechangestakeplace.Thewholeofthebody,atfirst,canbebrokenupinto"cells,"whichbecomeinoneplacemetamorphosedintomuscle,--inanotherplaceintogristleandbone,--inanotherplaceintofibroustissue,--andinanotherintohair;everypart

becominggraduallyandslowlyfashioned,asiftherewereanartificeratworkineachofthesecomplexstructuresthatwehavementioned.Thisembryo,asitiscalled,thenpassesintootherconditions.Ishouldtellyouthatthereisatimewhentheembryosofneitherdog,norhorse,norporpoise,normonkey,norman,canbedistinguishedbyanyessentialfeatureonefromtheother;thereisatimewhentheyeachandallofthemresemblethisoneoftheDog.Butasdevelopmentadvances,allthepartsacquiretheirspeciality,tillatlengthyouhavetheembryoconvertedintotheformoftheparentfromwhichitstarted.Sothatyousee,thislivinganimal,thishorse,beginsitsexistenceasaminuteparticleofnitrogenousmatter,which,beingsuppliedwithnutriment(derived,asIhaveshown,fromtheinorganicworld),growsupaccordingtothespecialtypeandconstructionofitsparents,worksand

undergoesaconstantwaste,andthatwasteismadegoodbynutrimentderivedfromtheinorganicworld;thewastegivenoffinthiswaybeingdirectlyaddedtotheinorganicworld;andeventuallytheanimalitselfdies,and,bytheprocessofdecomposition,itswholebodyisreturnedtothoseconditionsofinorganicmatterinwhichitssubstanceoriginated.

This,then,isthatwhichistrueofeverylivingform,fromthelowestplanttothehighestanimal--tomanhimself.YoumightdefinethelifeofeveryoneinexactlythesametermsasthosewhichIhavenowused;thedifferencebetweenthehighestandthelowestbeingsimplyinthecomplexityofthedevelopmentalchanges,thevarietyofthestructuralforms,thediversityofthephysiologicalfunctionswhichareexertedby

each.

IfIweretotakeanoaktreeasaspecimenoftheplantworld,Ishouldfindthatitoriginatedinanacorn,which,too,commencedinacell;theacornisplacedintheground,anditveryspeedilybeginstoabsorbtheinorganicmattersIhavenamed,addsenormouslytoitsbulk,andwecanseeit,yearafteryear,extendingitselfupwardanddownward,attractingandappropriatingtoitselfinorganicmaterials,whichitvivifies,andeventually,asitripens,givesoffitsownproperacorns,whichagainrunthesamecourse.ButIneednotmultiplyexamples,--from


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thehighesttothelowesttheessentialfeaturesoflifearethesame,asIhavedescribedineachofthesecases.

Somuch,then,fortheseparticularfeaturesoftheorganicworld,whichyoucanunderstandandcomprehend,solongasyouconfineyourselftoonesortoflivingbeing,andstudythatonly.

But,asyouknow,horsesarenottheonlylivingcreaturesintheworld;andagain,horses,likeallotheranimals,havecertainlimits--areconfinedtoacertainareaonthesurfaceoftheearthonwhichwelive,--and,asthatisthesimplermatter,Imaytakethatfirst.Initswildstate,andbeforethediscoveryofAmerica,whenthenaturalstateofthingswasinterferedwithbytheSpaniards,theHorsewasonlytobefoundinpartsoftheearthwhichareknowntogeographersastheOldWorld;thatistosay,youmightmeetwithhorsesinEurope,Asia,orAfrica;buttherewerenoneinAustralia,andtherewerenonewhatsoeverinthewholecontinentofAmerica,fromLabradordowntoCapeHorn.Thisisanempiricalfact,anditiswhatiscalled,statedinthewayIhavegivenityou,the'GeographicalDistribution'oftheHorse.

WhyhorsesshouldbefoundinEurope,Asia,andAfrica,andnotinAmerica,isnotobvious;theexplanationthattheconditionsoflifeinAmericaareunfavourabletotheirexistence,andthat,therefore,theyhadnotbeencreatedthere,evidentlydoesnotapply;forwhenthe

invadingSpaniards,orourownyeomenfarmers,conveyedhorsestothesecountriesfortheirownuse,theywerefoundtothrivewellandmultiplyveryrapidly;andmanyareevennowrunningwildinthosecountries,andinaperfectlynaturalcondition.Now,supposeweweretodoforeveryanimalwhatwehaveheredonefortheHorse,--thatis,tomarkoffanddistinguishtheparticulardistrictorregiontowhicheachbelonged;andsupposingwetabulatedalltheseresults,thatwouldbecalledtheGeographicalDistributionofanimals,whileacorrespondingstudyofplantswouldyieldasaresulttheGeographicalDistributionofplants.

Ipassonfromthatnow,asImerelywishedtoexplaintoyouwhatImeantbytheuseoftheterm'GeographicalDistribution.'AsIsaid,thereisanotheraspect,andamuchmoreimportantone,andthatis,the

relationsofthevariousanimalstooneanother.TheHorseisaverywell-definedmatter-of-factsortofanimal,andweareallprettyfamiliarwithitsstructure.Idaresayitmayhavestruckyou,thatitresemblesverymuchnoothermemberoftheanimalkingdom,exceptperhapstheZebraortheAss.Butletmeaskyoutolookalongthesediagrams.HereistheskeletonoftheHorse,andheretheskeletonoftheDog.YouwillnoticethatwehaveintheHorseaskull,abackboneandribs,shoulder-bladesandhaunch-bones.Inthefore-limb,oneupperarm-bone,twoforearm-bones,wrist-bones(wronglycalledknee),andmiddlehand-bones,endinginthethreebonesofafinger,thelastofwhichissheathedinthehornyhoofofthefore-foot:inthehind-limb,onethigh-bone,twoleg-bones,anklebones,andmiddlefoot-bones,endinginthethreebonesofatoe,thelastofwhichisencasedinthehoofof

thehind-foot.NowturntotheDog'sskeleton.Wefindidenticallythesamebones,butmoreofthem,therebeingmoretoesineachfoot,andhencemoretoe-bones.

Well,thatisaverycuriousthing!ThefactisthattheDogandtheHorse--whenonegetsalookatthemwithouttheoutwardimpedimentsoftheskin--arefoundtobemadeinverymuchthesamesortoffashion.AndifIweretomakeatransversesectionoftheDog,IshouldfindthesameorgansthatIhavealreadyshownyouasformingpartsoftheHorse.Well,hereisanotherskeleton--thatofakindofLemur--youseehehas


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justthesamebones;andifIweretomakeatransversesectionofit,itwouldbejustthesameagain.Inyourmind'seyeturnhimround,soastoputhisbackboneinapositioninclinedobliquelyupwardsandforwards,justasinthenextthreediagrams,whichrepresenttheskeletonsofanOrang,aChimpanzee,aGorilla,andyoufindyouhavenotroubleinidentifyingthebonesthroughout;andlastlyturntotheendoftheseries,thediagramrepresentingaman'sskeleton,andstillyoufindnogreatstructuralfeatureessentiallyaltered.Therearethesamebonesinthesamerelations.FromtheHorsewepassonandon,withgradualsteps,untilwearriveatlastatthehighestknownforms.Ontheotherhand,taketheotherlineofdiagrams,andpassfromtheHorsedownwardsinthescaletothisfish;andstill,thoughthemodificationsarevastlygreater,theessentialframeworkoftheorganizationremainsunchanged.Here,forinstance,isaPorpoise:hereisitsstrongbackbone,withthecavityrunningthroughit,whichcontainsthespinalcord;herearetheribs,heretheshoulderblade;hereisthelittleshortupper-armbone,herearethetwoforearmbones,thewrist-bone,andthefinger-bones.

Strange,isitnot,thatthePorpoiseshouldhaveinthisqueer-lookingaffair--itsflapper(asitiscalled),thesamefundamentalelementsasthefore-legoftheHorseortheDog,ortheApeorMan;andhereyouwillnoticeaverycuriousthing,--thehinderlimbsareabsent.Now,letusmakeanotherjump.LetusgototheCodfish:hereyouseeisthe

forearm,inthislargepectoralfin--carryingyourmind'seyeonwardfromtheflapperofthePorpoise.Andhereyouhavethehinderlimbsrestoredintheshapeoftheseventralfins.IfIweretomakeatransversesectionofthis,Ishouldfindjustthesameorgansthatwehavebeforenoticed.Sothat,yousee,therecomesoutthisstrangeconclusionastheresultofourinvestigations,thattheHorse,whenexaminedandcomparedwithotheranimals,isfoundbynomeanstostandaloneinnature;butthatthereareanenormousnumberofothercreatureswhichhavebackbones,ribs,andlegs,andotherpartsarrangedinthesamegeneralmanner,andinalltheirformationexhibitingthesamebroadpeculiarities.

Iamsurethatyoucannothavefollowedmeeveninthisextremely

elementaryexpositionofthestructuralrelationsofanimals,withoutseeingwhatIhavebeendrivingatallthrough,whichis,toshowyouthat,stepbystep,naturalistshavecometotheideaofaunityofplan,orconformityofconstruction,amonganimalswhichappearedatfirstsighttobeextremelydissimilar.

Andhereyouhaveevidenceofsuchaunityofplanamongalltheanimalswhichhavebackbones,andwhichwetechnicallycall"Vertebrata".Buttherearemultitudesofotheranimals,suchascrabs,lobsters,spiders,andsoon,whichweterm"Annulosa".IntheseIcouldnotpointouttoyouthepartsthatcorrespondwiththoseoftheHorse,--thebackbone,forinstance,--astheyareconstructeduponaverydifferentprinciple,whichisalsocommontoallofthem;thatistosay,theLobster,the

Spider,andtheCentipede,haveacommonplanrunningthroughtheirwholearrangement,injustthesamewaythattheHorse,theDog,andthePorpoiseassimilatetoeachother.

Yetothercreatures--whelks,cuttlefishes,oysters,snails,andalltheirtribe("Mollusca")--resembleoneanotherinthesameway,butdifferfromboth"Vertebrata"and"Annulosa";andthelikeistrueoftheanimalscalled"Coelenterata"(Polypes)and"Protozoa"(animalculesandsponges).


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Now,bypursuingthissortofcomparison,naturalistshavearrivedattheconvictionthatthereare,--somethinkfive,andsomeseven,--butcertainlynotmorethanthelatternumber--andperhapsitissimplertoassumefive--distinctplansorconstructionsinthewholeoftheanimalworld;andthatthehundredsofthousandsofspeciesofcreaturesonthesurfaceoftheearth,areallreducibletothosefive,or,atmost,seven,plansoforganization.

Butcanwegonofurtherthanthat?Whenonehasgotsofar,oneistemptedtogoonastepandinquirewhetherwecannotgobackyetfurtherandbringdownthewholetomodificationsofoneprimordialunit.Theanatomistcannotdothis;butifhecalltohisaidthestudyofdevelopment,hecandoit.Forweshallfindthat,distinctasthoseplansare,whetheritbeaporpoiseorman,orlobster,oranyofthoseotherkindsIhavementioned,everyonebeginsitsexistencewithoneandthesameprimitiveform,--thatoftheegg,consisting,aswehaveseen,ofanitrogenoussubstance,havingasmallparticleornucleusinthecentreofit.Furthermore,theearlierchangesofeacharesubstantiallythesame.Anditisinthisthatliesthattrue"unityoforganization"oftheanimalkingdomwhichhasbeenguessedatandfanciedformanyyears;butwhichithasbeenlefttothepresenttimetobedemonstratedbythecarefulstudyofdevelopment.Butisitpossibletogoanotherstepfurtherstill,andtoshowthatinthesamewaythewholeoftheorganicworldisreducibletooneprimitive

conditionofform?Isthereamongtheplantsthesameprimitiveformoforganization,andisthatidenticalwiththatoftheanimalkingdom?Thereplytothatquestion,too,isnotuncertainordoubtful.Itisnowprovedthateveryplantbeginsitsexistenceunderthesameform;thatistosay,inthatofacell--aparticleofnitrogenousmatterhavingsubstantiallythesameconditions.Sothatifyoutracebacktheoaktoitsfirstgerm,oraman,orahorse,orlobster,oroyster,oranyotheranimalyouchoosetoname,youshallfindeachandallofthesecommencingtheirexistenceinformsessentiallysimilartoeachother:and,furthermore,thatthefirstprocessesofgrowth,andmanyofthesubsequentmodifications,areessentiallythesameinprincipleinalmostall.

Inconclusion,letme,inafewwords,recapitulatethepositionswhichIhavelaiddown.AndyoumustunderstandthatIhavenotbeentalkingmeretheory;IhavebeenspeakingofmatterswhichareasplainlydemonstrableasthecommonestpropositionsofEuclid--offactsthatmustformthebasisofallspeculationsandbeliefsinBiologicalscience.Wehavegraduallytraceddownallorganicforms,or,inotherwords,wehaveanalyzedthepresentconditionofanimatednature,untilwefoundthateachspeciestookitsorigininaformsimilartothatunderwhichalltheotherscommencetheirexistence.Wehavefoundthewholeofthevastarrayoflivingforms,withwhichwearesurrounded,constantlygrowing,increasing,decayinganddisappearing;theanimalconstantlyattracting,modifying,andapplyingtoitssustenancethematterofthevegetablekingdom,whichderiveditssupportfromtheabsorptionand

conversionofinorganicmatter.Andsoconstantanduniversalisthisabsorption,waste,andreproduction,thatitmaybesaidwithperfectcertaintythatthereisleftinnooneofourbodiesatthepresentmomentamillionthpartofthematterofwhichtheywereoriginallyformed!Wehaveseen,again,thatnotonlyisthelivingmatterderivedfromtheinorganicworld,butthattheforcesofthatmatterareallofthemcorrelativewithandconvertibleintothoseofinorganicnature.

This,forourpresentpurposes,isthebestviewofthepresentconditionoforganicnaturewhichIcanlaybeforeyou:itgivesyouthe


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greatoutlinesofavastpicture,whichyoumustfillupbyyourownstudy.

InthenextlectureIshallendeavourinthesamewaytogobackintothepast,andtosketchinthesamebroadmannerthehistoryoflifeinepochsprecedingourown.

EndofThePresentConditionofOrganicNature.

***

THEPASTCONDITIONOFORGANICNATURE.

InthelecturewhichIdeliveredlastMondayevening,Iendeavouredtosketchinaverybriefmanner,butaswellasthetimeatmydisposalwouldpermit,thepresentconditionoforganicnature,meaningbythatlargetitlesimplyanindicationofthegreat,broad,andgeneralprincipleswhicharetobediscoveredbythosewholookattentivelyatthephenomenaoforganicnatureasatpresentdisplayed.Thegeneralresultofourinvestigationsmightbesummedupthus:wefoundthatthemultiplicityoftheformsofanimallife,greatasthatmaybe,maybereducedtoacomparativelyfewprimitiveplansortypesofconstruction;thatafurtherstudyofthedevelopmentofthosedifferentforms

revealedtousthattheywereagainreducible,untilweatlastbroughttheinfinitediversityofanimal,andevenvegetablelife,downtotheprimordialformofasinglecell.

Wefoundthatouranalysisoftheorganicworld,whetheranimalsorplants,showed,inthelongrun,thattheymightbothbereducedinto,andwere,infact,composedof,thesameconstituents.Andwesawthattheplantobtainedthematerialsconstitutingitssubstancebyapeculiarcombinationofmattersbelongingentirelytotheinorganicworld;that,then,theanimalwasconstantlyappropriatingthenitrogenousmattersoftheplanttoitsownnourishment,andreturningthembacktotheinorganicworld,inwhatwespokeofasitswaste;andthatfinally,whentheanimalceasedtoexist,theconstituentsofits

bodyweredissolvedandtransmittedtothatinorganicworldwhencetheyhadbeenatfirstabstracted.Thuswesawinboththebladeofgrassandthehorsebutthesameelementsdifferentlycombinedandarranged.Wediscoveredacontinualcirculationgoingon,--theplantdrawingintheelementsofinorganicnatureandcombiningthemintofoodfortheanimalcreation;theanimalborrowingfromtheplantthematterforitsownsupport,givingoffduringitslifeproductswhichreturnedimmediatelytotheinorganicworld;andthat,eventually,theconstituentmaterialsofthewholestructureofbothanimalsandplantswerethusreturnedtotheiroriginalsource:therewasaconstantpassagefromonestateofexistencetoanother,andareturningbackagain.

Lastly,whenweendeavouredtoformsomenotionofthenatureofthe

forcesexercisedbylivingbeings,wediscoveredthatthey--ifnotcapableofbeingsubjectedtothesameminuteanalysisastheconstituentsofthosebeingsthemselves--thattheywerecorrelativewith--thattheyweretheequivalentsoftheforcesofinorganicnature--thattheywere,inthesenseinwhichthetermisnowused,convertiblewiththem.Thatwasourgeneralresult.

Andnow,leavingthePresent,ImustendeavourinthesamemannertoputbeforeyouthefactsthataretobediscoveredinthePasthistoryofthelivingworld,inthepastconditionsoforganicnature.Wehave,


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to-night,todealwiththefactsofthathistory--ahistoryinvolvingperiodsoftimebeforewhichourmerehumanrecordssinkintoutterinsignificance--ahistorythevarietyandphysicalmagnitudeofwhoseeventscannotevenbeforeshadowedbythehistoryofhumanlifeandhumanphenomena--ahistoryofthemostvariedandcomplexcharacter.

Wemustdealwiththehistory,then,inthefirstplace,asweshoulddealwithallotherhistories.Thehistoricalstudentknowsthathisfirstbusinessshouldbetoinquireintothevalidityofhisevidence,andthenatureoftherecordinwhichtheevidenceiscontained,thathemaybeabletoformaproperestimateofthecorrectnessoftheconclusionswhichhavebeendrawnfromthatevidence.So,here,wemustpass,inthefirstplace,totheconsiderationofamatterwhichmayseemforeigntothequestionunderdiscussion.Wemustdwelluponthenatureoftherecords,andthecredibilityoftheevidencetheycontain;wemustlooktothecompletenessorincompletenessofthoserecordsthemselves,beforeweturntothatwhichtheycontainandreveal.Thequestionofthecredibilityofthehistory,happilyforus,willnotrequiremuchconsideration,for,inthishistory,unlikethoseofhumanorigin,therecanbenocavilling,nodifferencesastotherealityandtruthofthefactsofwhichitismadeup;thefactsstatethemselves,andarelaidoutclearlybeforeus.

But,althoughoneofthegreatestdifficultiesofthehistoricalstudent

isclearedoutofourpath,thereareotherdifficulties--difficultiesinrightlyinterpretingthefactsastheyarepresentedtous--whichmaybecomparedwiththegreatestdifficultiesofanyotherkindsofhistoricalstudy.

Whatisthisrecordofthepasthistoryoftheglobe,andwhatarethequestionswhichareinvolvedinaninquiryintoitscompletenessorincompleteness?Thatrecordiscomposedofmud;andthequestionwhichwehavetoinvestigatethiseveningresolvesitselfintoaquestionoftheformationofmud.Youmaythink,perhaps,thatthisisavaststep--ofalmostfromthesublimetotheridiculous--fromthecontemplationofthehistoryofthepastagesoftheworld'sexistencetotheconsiderationofthehistoryoftheformationofmud!But,in

nature,thereisnothingmeanandunworthyofattention;thereisnothingridiculousorcontemptibleinanyofherworks;andthisinquiry,youwillsoonsee,Ihope,takesustotheveryrootandfoundationsofoursubject.

How,then,ismudformed?Always,withsometriflingexception,whichIneednotconsidernow--always,astheresultoftheactionofwater,wearingdownanddisintegratingthesurfaceoftheearthandrockswithwhichitcomesincontact--poundingandgrindingitdown,andcarryingtheparticlesawaytoplaceswheretheyceasetobedisturbedbythismechanicalaction,andwheretheycansubsideandrest.Fortheocean,urgedbywinds,washes,asweknow,alongextentofcoast,andeverywave,loadedasitiswithparticlesofsandandgravelasitbreaks

upontheshore,doessomethingtowardsthedisintegratingprocess.Andthus,slowlybutsurely,thehardestrocksaregraduallygrounddowntoapowderysubstance;andthemudthusformed,coarserorfiner,asthecasemaybe,iscarriedbytherushofthetides,orcurrents,tillitreachesthecomparativelydeeperpartsoftheocean,inwhichitcansinktothebottom,thatis,topartswherethereisadepthofaboutfourteenorfifteenfathoms,adepthatwhichthewateris,usually,nearlymotionless,andinwhich,ofcourse,thefinerparticlesofthisdetritus,ormudaswecallit,sinkstothebottom.


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Or,again,ifyoutakeariver,rushingdownfromitsmountainsources,brawlingoverthestonesandrocksthatintersectitspath,loosening,removing,andcarryingwithitinitsdownwardcoursethepebblesandlightermattersfromitsbanks,itcrushesandpoundsdowntherocksandearthsinpreciselythesamewayasthewearingactionoftheseawaves.Themattersformingthedepositaretornfromthemountain-sideandwhirledimpetuouslyintothevalley,moreslowlyovertheplain,thenceintotheestuary,andfromtheestuarytheyaresweptintothesea.Thecoarserandheavierfragmentsareobviouslydepositedfirst,thatis,assoonasthecurrentbeginstoloseitsforcebybecomingamalgamatedwiththestillerdepthsoftheocean,butthefinerandlighterparticlesarecarriedfurtheron,andeventuallydepositedinadeeperandstillerportionoftheocean.

Itclearlyfollowsfromthisthatmudgivesusachronology;foritisevidentthatsupposingthis,whichInowsketch,tobetheseabottom,andsupposingthistobeacoast-line;fromthewashingactionoftheseaupontherock,wearingandgrindingitdownintoasedimentofmud,themudwillbecarrieddown,andatlength,depositedinthedeeperpartsofthisseabottom,whereitwillformalayer;andthen,whilethatfirstlayerishardening,othermudwhichiscomingfromthesamesourcewill,ofcourse,becarriedtothesameplace;and,asitisquiteimpossibleforittogetbeneaththelayeralreadythere,itdepositsitselfaboveit,andformsanotherlayer,andinthatwayyou

graduallyhavelayersofmudconstantlyformingandhardeningoneabovetheother,andconveyingarecordoftime.

Itisanecessaryresultoftheoperationofthelawofgravitationthattheuppermostlayershallbetheyoungestandthelowesttheoldest,andthatthedifferentbedsshallbeolderatanyparticularpointorspotinexactlytheratiooftheirdepthfromthesurface.Sothatiftheywereupheavedafterwards,andyouhadaseriesofthesedifferentlayersofmud,convertedintosandstone,orlimestone,asthecasemightbe,youmightbesurethatthebottomlayerwasdepositedfirst,andthattheupperlayerswereformedafterwards.Here,yousee,isthefirststepinthehistory--theselayersofmudgiveusanideaoftime.

Thewholesurfaceoftheearth,--Ispeakbroadly,andleaveoutminorqualifications,--ismadeupofsuchlayersofmud,sohard,themajorityofthem,thatwecallthemrockwhetherlimestoneorsandstone,orothervarietiesofrock.And,seeingthateverypartofthecrustoftheearthismadeupinthisway,youmightthinkthatthedeterminationofthechronology,thefixingofthetimewhichithastakentoformthiscrustisacomparativelysimplematter.Takeabroadaverage,ascertainhowfastthemudisdepositeduponthebottomofthesea,orintheestuaryofrivers;takeittobeaninch,ortwo,orthreeinchesayear,orwhateveryoumayroughlyestimateitat;thentakethetotalthicknessofthewholeseriesofstratifiedrocks,whichgeologistsestimateattwelveorthirteenmiles,oraboutseventythousandfeet,makeasuminshortdivision,dividethetotalthicknessbythatofthequantity

depositedinoneyear,andtheresultwill,ofcourse,giveyouthenumberofyearswhichthecrusthastakentoform.

Truly,thatlooksaverysimpleprocess!Itwouldbesoexceptforcertaindifficulties,theveryfirstofwhichisthatoffindinghowrapidlysedimentsaredeposited;butthemaindifficulty--adifficultywhichrendersanycertaincalculationsofsuchamatteroutofthequestion--isthis,thesea-bottomonwhichthedeposittakesplaceiscontinuallyshifting.


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Insteadofthesurfaceoftheearthbeingthatstable,fixedthingthatitispopularlybelievedtobe,being,incommonparlance,theveryemblemoffixityitself,itisincessantlymoving,andis,infact,asunstableasthesurfaceofthesea,exceptthatitsundulationsareinfinitelyslowerandenormouslyhigheranddeeper.

Now,whatistheeffectofthisoscillation?TakethecasetowhichIhavepreviouslyreferred.Thefinerorcoarsersedimentsthatarecarrieddownbythecurrentoftheriver,willonlybecarriedoutacertaindistance,andeventually,aswehavealreadyseen,onreachingthestillerpartoftheocean,willbedepositedatthebottom.

(FIGURE4.Sectionthroughdepositsonsea-bottomandshore.)

LetCy(Figure4)bethesea-bottom,yDtheshore,xythesea-level,thenthecoarserdepositwillsubsideovertheregionB,thefineroverA,whilebeyondAtherewillbenodepositatall;and,consequently,norecordwillbekept,simplybecausenodepositisgoingon.Now,supposethatthewholeland,C,D,whichwehaveregardedasstationary,goesdown,asitdoesso,bothAandBgofurtheroutfromtheshore,whichwillbeatyl;x1,y1,beingthenewsea-level.Theconsequencewillbethatthelayerofmud(A),beingnow,forthemostpart,furtherthantheforceofthecurrentisstrongenoughtoconveyeventhefinest'debris',will,ofcourse,receivenomoredeposits,andhavingattained

acertainthicknesswillnowgrownothicker.

Weshouldbemisledintakingthethicknessofthatlayer,wheneveritmaybeexposedtoourview,asarecordoftimeinthemannerinwhichwearenowregardingthissubject,asitwouldgiveusonlyanimperfectandpartialrecord:itwouldseemtorepresenttooshortaperiodoftime.

Suppose,ontheotherhand,thattheland(CD)hadgoneonrisingslowlyandgradually--sayaninchortwoinchesinthecourseofacentury,--whatwouldbethepracticaleffectofthatmovement?Why,thatthesedimentAandBwhichhasbeenalreadydeposited,wouldeventuallybebroughtnearertotheshore-level,andagainsubjectedtothewear

andtearofthesea;anddirectlytheseabeginstoactuponit,itwouldofcoursesooncutupandcarryitaway,toagreaterorlessextent,tobere-depositedfurtherout.

Well,asthereis,inallprobability,notonesinglespotonthewholesurfaceoftheearth,whichhasnotbeenupanddowninthiswayagreatmanytimes,itfollowsthatthethicknessofthedepositsformedatanyparticularspotcannotbetaken(evensupposingwehadatfirstobtainedcorrectdataastotherateatwhichtheytookplace)asaffordingreliableinformationastotheperiodoftimeoccupiedinitsdeposit.Sothatyouseeitisabsolutelynecessaryfromthesefacts,seeingthatourrecordentirelyconsistsofaccumulationsofmud,superimposedoneontheother;seeinginthenextplacethatanyparticularspotson

whichaccumulationshaveoccurred,havebeenconstantlymovingupanddown,andsometimesoutofthereachofadeposit,andatothertimesitsowndepositbrokenupandcarriedaway,itfollowsthatourrecordmustbeinthehighestdegreeimperfect,andwehavehardlyatraceleftofthickdeposits,oranydefiniteknowledgeoftheareathattheyoccupied,inagreatmanycases.Andmarkthis!Thatsupposingeventhatthewholesurfaceoftheearthhadbeenaccessibletothegeologist,--thatmanhadhadaccesstoeverypartoftheearth,andhadmadesectionsofthewhole,andputthemalltogether,--eventhenhisrecordmustofnecessitybeimperfect.


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Buttohowmuchhasmanreallyaccess?IfyouwilllookatthisMapyouwillseethatitrepresentstheproportionoftheseatotheearth:thiscolouredpartindicatesallthedryland,andthisotherportionisthewater.Youwillnoticeatoncethatthewatercoversthree-fifthsofthewholesurfaceoftheglobe,andhascovereditinthesamemannereversincemanhaskeptanyrecordofhisownobservations,tosaynothingoftheminuteperiodduringwhichhehascultivatedgeologicalinquiry.Sothatthree-fifthsofthesurfaceoftheearthisshutoutfromusbecauseitisunderthesea.Letuslookattheothertwo-fifths,andseewhatarethecountriesinwhichanythingthatmaybetermedsearchinggeologicalinquiryhasbeencarriedout:agooddealofFrance,Germany,andGreatBritainandIreland,bitsofSpain,ofItaly,andofRussia,havebeenexamined,butofthewholegreatmassofAfrica,exceptpartsofthesouthernextremity,weknownexttonothing;littlebitsofIndia,butofthegreaterpartoftheAsiaticcontinentnothing;bitsoftheNorthernAmericanStatesandofCanada,butofthegreaterpartofthecontinentofNorthAmerica,andinstilllargerproportion,ofSouthAmerica,nothing!

Underthesecircumstances,itfollowsthatevenwithreferencetothatkindofimperfectinformationwhichwecanpossess,itisonlyofabouttheten-thousandthpartoftheaccessiblepartsoftheearththathasbeenexaminedproperly.Therefore,itiswithjusticethatthemost

thoughtfulofthosewhoareconcernedintheseinquiriesinsistcontinuallyupontheimperfectionofthegeologicalrecord;for,Irepeat,itisabsolutelynecessary,fromthenatureofthings,thatthatrecordshouldbeofthemostfragmentaryandimperfectcharacter.Unfortunatelythiscircumstancehasbeenconstantlyforgotten.Menofscience,likeyoungcoltsinafreshpasture,areapttobeexhilaratedonbeingturnedintoanewfieldofinquiry,togooffatahand-gallop,intotaldisregardofhedgesandditches,losingsightofthereallimitationoftheirinquiries,andtoforgettheextremeimperfectionofwhatisreallyknown.Geologistshaveimaginedthattheycouldtelluswhatwasgoingonatallpartsoftheearth'ssurfaceduringagivenepoch;theyhavetalkedofthisdepositbeingcontemporaneouswiththatdeposit,until,fromourlittlelocalhistoriesofthechangesat

limitedspotsoftheearth'ssurface,theyhaveconstructedauniversalhistoryoftheglobeasfullofwondersandportentsasanyotherstoryofantiquity.

Butwhatdoesthisattempttoconstructauniversalhistoryoftheglobeimply?Itimpliesthatweshallnotonlyhaveapreciseknowledgeoftheeventswhichhaveoccurredatanyparticularpoint,butthatweshallbeabletosaywhatevents,atanyonespot,tookplaceatthesametimewiththoseatotherspots.

(FIGURE5.Sectionthroughtwobedsofmud.)

Letusseehowfarthatisinthenatureofthingspracticable.Suppose

thathereImakeasectionoftheLakeofKillarney,andherethesectionofanotherlake--thatofLochLomondinScotlandforinstance.Theriversthatflowintothemareconstantlycarryingdowndepositsofmud,andbeds,orstrata,arebeingasconstantlyformed,oneabovetheother,atthebottomofthoselakes.Now,thereisnotashadowofdoubtthatinthesetwolakesthelowerbedsareallolderthantheupper--thereisnodoubtaboutthat;butwhatdoes'this'tellusabouttheageofanygivenbedinLochLomond,ascomparedwiththatofanygivenbedintheLakeofKillarney?Itis,indeed,obviousthatifanytwosetsofdepositsareseparatedanddiscontinuous,thereis


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absolutelynomeanswhatevergivenyoubythenatureofthedepositofsayingwhetheroneismuchyoungerorolderthantheother;butyoumaysay,asmanyhavesaidandthink,thatthecaseisverymuchalteredifthebedswhichwearecomparingarecontinuous.Supposetwobedsofmudhardenedintorock,--AandB--areseeninsection.(Figure5.)

Well,yousay,itisadmittedthatthelowermostbedisalwaystheolder.Verywell;B,therefore,isolderthanA.Nodoubt,'asawhole',itisso;orifanypartsofthetwobedswhichareinthesameverticallinearecompared,itisso.Butsupposeyoutakewhatseemsaverynaturalstepfurther,andsaythatthepart'a'ofthebedAisyoungerthanthepart'b'ofthebedB.Isthissoundreasoning?Ifyoufindanyrecordofchangestakingplaceat'b',didtheyoccurbeforeanyeventswhichtookplacewhile'a'wasbeingdeposited?Itlooksallveryplainsailing,indeed,tosaythattheydid;andyetthereisnoproofofanythingofthekind.AstheformerDirectorofthisInstitution,SirH.DelaBeche,longagoshowed,thisreasoningmayinvolveanentirefallacy.Itisextremelypossiblethat'a'mayhavebeendepositedagesbefore'b'.Itisveryeasytounderstandhowthatcanbe.ToreturntoFigure4;whenAandBweredeposited,theywere'substantially'contemporaneous;Abeingsimplythefinerdeposit,andBthecoarserofthesamedetritusorwasteofland.Nowsupposethatthatsea-bottomgoesdown(asshowninFigure4),sothatthefirstdepositiscarriednofartherthan'a',formingthebedAl,andthecoarsenofartherthan

'b',formingthebedB1,theresultwillbetheformationoftwocontinuousbeds,oneoffinesediment(AA1)over-lappinganotherofcoarsesediment(BBl).Nowsupposethewholesea-bottomisraisedup,andasectionexposedaboutthepointAl;nodoubt,ATTHISSPOT,theupperbedisyoungerthanthelower.ButweshouldobviouslygreatlyerrifweconcludedthatthemassoftheupperbedatAwasyoungerthanthelowerbedatB;forwehavejustseenthattheyarecontemporaneousdeposits.StillmoreshouldwebeinerrorifwesupposedtheupperbedatAtobeyoungerthanthecontinuationofthelowerbedatBl;forAwasdepositedlongbeforeB1.Infine,if,insteadofcomparingimmediatelyadjacentpartsoftwobeds,oneofwhichliesuponanother,wecomparedistantparts,itisquitepossiblethattheuppermaybeanynumberofyearsolderthantheunder,andtheunderanynumberofyears

youngerthantheupper.

NowyoumustnotsupposethatIputthisbeforeyouforthepurposeofraisingaparadoxicaldifficulty;thefactis,thatthegreatmassofdepositshavetakenplaceinsea-bottomswhicharegraduallysinking,andhavebeenformedundertheveryconditionsIamheresupposing.

DonotrunawaywiththenotionthatthissubvertstheprincipleIlaiddownatfirst.Theerrorliesinextendingaprinciplewhichisperfectlyapplicabletodepositsinthesameverticallinetodepositswhicharenotinthatrelationtooneanother.

Itisinconsequenceofcircumstancesofthiskind,andofothersthatI

mightmentiontoyou,thatourconclusionsonandinterpretationsoftherecordarereallyandstrictlyonlyvalidsolongasweconfineourselvestooneverticalsection.Idonotmeantotellyouthattherearenoqualifyingcircumstances,sothat,eveninveryconsiderableareas,wemaysafelyspeakofconformablysuperimposedbedsbeingolderoryoungerthanothersatmanydifferentpoints.Butwecanneverbequitesureincomingtothatconclusion,andespeciallywecannothesureifthereisanybreakintheircontinuity,oranyverygreatdistancebetweenthepointstobecompared.


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Wellnow,somuchfortherecorditself,--somuchforitsimperfections,--somuchfortheconditionstobeobservedininterpretingit,anditschronologicalindications,themomentwepassbeyondthelimitsofaverticallinearsection.

Nowletuspassfromtherecordtothatwhichitcontains,--fromthebookitselftothewritingandthefiguresonitspages.Thiswritingandthesefiguresconsistofremainsofanimalsandplantswhich,inthegreatmajorityofcases,havelivedanddiedintheveryspotinwhichwenowfindthem,oratleastintheimmediatevicinity.Youmustallofyoubeaware--andIreferredtothefactinmylastlecture--thattherearevastnumbersofcreatureslivingatthebottomofthesea.Thesecreatures,likeallothers,soonerorlaterdie,andtheirshellsandhardpartslieatthebottom;andthenthefinemudwhichisbeingconstantlybroughtdownbyriversandtheactionofthewearandtearofthesea,coversthemoverandprotectsthemfromanyfurtherchangeoralteration;and,ofcourse,asinprocessoftimethemudbecomeshardenedandsolidified,theshellsoftheseanimalsarepreservedandfirmlyimbeddedinthelimestoneorsandstonewhichisbeingthusformed.YoumayseeinthegalleriesoftheMuseumupstairsspecimensoflimestonesinwhichsuchfossilremainsofexistinganimalsareimbedded.Therearesomespecimensinwhichturtles'eggshavebeenimbeddedincalcareoussand,andbeforethesunhadhatchedtheyoungturtles,theybecamecoveredoverwithcalcareousmud,andthushave

beenpreservedandfossilized.

Notonlydoesthisprocessofimbeddingandfossilizationoccurwithmarineandotheraquaticanimalsandplants,butitaffectsthoselandanimalsandplantswhicharedriftedawaytosea,orbecomeburiedinbogsormorasses;andtheanimalswhichhavebeentroddendownbytheirfellowsandcrushedinthemudattheriver'sbank,astheherdhavecometodrink.Inanyofthesecases,theorganismsmaybecrushedorbemutilated,beforeorafterputrefaction,insuchamannerthatperhapsonlyapartwillbeleftintheforminwhichitreachesus.Itis,indeed,amostremarkablefact,thatitisquiteanexceptionalcasetofindaskeletonofanyoneofallthethousandsofwildlandanimalsthatweknowareconstantlybeingkilled,ordyinginthecourseof

nature:theyarepreyedonanddevouredbyotheranimalsordieinplaceswheretheirbodiesarenotafterwardsprotectedbymud.Thereareotheranimalsexistinginthesea,theshellsofwhichformexceedinglylargedeposits.YouareprobablyawarethatbeforetheattemptwasmadetolaytheAtlantictelegraphiccable,theGovernmentemployedvesselsinmakingaseriesofverycarefulobservationsandsoundingsofthebottomoftheAtlantic;andalthough,aswemustallregret,uptothepresenttimethatprojecthasnotsucceeded,wehavethesatisfactionofknowingthatityieldedsomemostremarkableresultstoscience.TheAtlanticOceanhadtobesoundedrightacross,todepthsofseveralmilesinsomeplaces,andthenatureofitsbottomwascarefullyascertained.Well,now,aspaceofabout1,000mileswidefromeasttowest,andIdonotexactlyknowhowmanyfromnorthtosouth,butatany

rate600or700miles,wascarefullyexamined,anditwasfoundthatoverthewholeofthatimmenseareaanexcessivelyfinechalkymudisbeingdeposited;andthisdepositisentirelymadeupofanimalswhosehardpartsaredepositedinthispartoftheocean,andaredoubtlessgraduallyacquiringsolidityandbecomingmetamorphosedintoachalkylimestone.Thus,yousee,itisquitepossibleinthiswaytopreserveunmistakablerecordsofanimalandvegetablelife.Wheneverthesea-bottom,bysomeofthoseundulationsoftheearth'scrustthatIhavereferredto,becomesupheaved,andsectionsorboringsaremade,orpitsaredug,thenwebecomeabletoexaminethecontentsand


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constituentsoftheseancientsea-bottoms,andfindoutwhatmannerofanimalslivedatthatperiod.

Nowitisaveryimportantconsiderationinitsbearingonthecompletenessoftherecord,toinquirehowfartheremainscontainedinthesefossiliferouslimestonesareabletoconveyanythinglikeanaccurateorcompleteaccountoftheanimalswhichwereinexistenceatthetimeofitsformation.Uponthatpointwecanformaveryclearjudgment,andoneinwhichthereisnopossibleroomforanymistake.Thereareofcourseagreatnumberofanimals--suchasjelly-fishes,andotheranimals--withoutanyhardparts,ofwhichwecannotreasonablyexpecttofindanytraceswhatever:thereisnothingofthemtopreserve.Withinaveryshorttime,youwillhavenoticed,aftertheyareremovedfromthewater,theydryuptoamerenothing;certainlytheyarenotofanaturetoleaveanyveryvisibletracesoftheirexistenceonsuchbodiesaschalkormud.Thenagain,lookatlandanimals;itis,asIhavesaid,averyuncommonthingtofindalandanimalentireafterdeath.Insectsandothercarnivorousanimalsveryspeedilypullthemtopieces,putrefactiontakesplace,andso,outofthehundredsofthousandsthatareknowntodieeveryyear,itistherarestthingintheworldtoseeoneimbeddedinsuchawaythatitsremainswouldbepreservedforalengthenedperiod.Notonlyisthisthecase,butevenwhenanimalremainshavebeensafelyimbedded,certainnaturalagentsmaywhollydestroyandremovethem.

Almostallthehardpartsofanimals--thebonesandsoon--arecomposedchieflyofphosphateoflimeandcarbonateoflime.Someyearsago,IhadtomakeaninquiryintothenatureofsomeverycuriousfossilssenttomefromtheNorthofScotland.FossilsareusuallyhardbonystructuresthathavebecomeimbeddedinthewayIhavedescribed,andhavegraduallyacquiredthenatureandsolidityofthebodywithwhichtheyareassociated;butinthiscaseIhadaseriesof'holes'insomepiecesofrock,andnothingelse.Thoseholes,however,hadacertaindefiniteshapeaboutthem,andwhenIgotaskilfulworkmantomakecastingsoftheinterioroftheseholes,Ifoundthattheyweretheimpressionsofthejointsofabackboneandofthearmourofagreatreptile,twelveormorefeetlong.Thisgreatbeasthaddiedandgot

buriedinthesand;thesandhadgraduallyhardenedoverthebones,butremainedporous.Waterhadtrickledthroughit,andthatwaterbeingprobablychargedwithasuperfluityofcarbonicacid,haddissolvedallthephosphateandcarbonateoflime,andthebonesthemselveshadthusdecayedandentirelydisappeared;butasthesandstonehappenedtohaveconsolidatedbythattime,thepreciseshapeoftheboneswasretained.Ifthatsandstonehadremainedsoftalittlelonger,weshouldhaveknownnothingwhatsoeveroftheexistenceofthereptilewhosebonesithadencased.

Howcertainitisthatavastnumberofanimalswhichhaveexistedatoneperiodonthisearthhaveentirelyperished,andleftnotracewhateveroftheirforms,maybeprovedtoyoubyotherconsiderations.

Therearelargetractsofsandstoneinvariouspartsoftheworld,inwhichnobodyhasyetfoundanythingbutfootsteps.Notaboneofanydescription,butanenormousnumberoftracesoffootsteps.Thereisnoquestionaboutthem.ThereisawholevalleyinConnecticutcoveredwiththesefootsteps,andnotasinglefragmentoftheanimalswhichmadethemhasyetbeenfound.Letmementionanothercasewhileuponthatmatter,whichisevenmoresurprisingthanthosetowhichIhaveyetreferred.ThereisalimestoneformationnearOxford,ataplacecalledStonesfield,whichhasyieldedtheremainsofcertainveryinterestingmammaliananimals,anduptothistime,ifIrecollectrightly,there


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havebeenfoundsevenspecimensofitslowerjaws,andnotabitofanythingelse,neitherlimb-bonesnorskull,oranypartwhatever;notafragmentofthewholesystem!Ofcourse,itwouldbepreposteroustoimaginethatthebeastshadnothingelsebutalowerjaw!Theprobabilityis,asDr.Bucklandshowed,astheresultofhisobservationsondeaddogsintheriverThames,thatthelowerjaw,notbeingsecuredbyveryfirmligamentstothebonesofthehead,andbeingaweightyaffair,wouldeasilybeknockedoff,ormightdropawayfromthebodyasitfloatedinwaterinastateofdecomposition.Thejawwouldthusbedepositedimmediately,whiletherestofthebodywouldfloatanddriftawayaltogether,ultimatelyreachingthesea,andperhapsbecomingdestroyed.Thejawbecomescoveredupandpreservedintheriversilt,andthusitcomesthatwehavesuchacuriouscircumstanceasthatofthelowerjawsintheStonesfieldslates.Sothat,yousee,faultyastheselayersofstoneintheearth'scrustare,defectiveastheynecessarilyareasarecord,theaccountofcontemporaneousvitalphenomenapresentedbythemis,bythenecessityofthecase,infinitelymoredefectiveandfragmentary.

ItwasnecessarythatIshouldputallthisverystronglybeforeyou,because,otherwise,youmighthavebeenledtothinkdifferentlyofthecompletenessofourknowledgebythenextfactsIshallstatetoyou.

Theresearchesofthelastthree-quartersofacenturyhave,intruth,

revealedawonderfulrichnessoforganiclifeinthoserocks.Certainlynotfewerthanthirtyorfortythousanddifferentspeciesoffossilshavebeendiscovered.Youhavenomoregroundfordoubtingthatthesecreaturesreallylivedanddiedatorneartheplacesinwhichwefindthemthanyouhaveforlikescepticismaboutashellonthesea-shore.Theevidenceisasgoodintheonecaseasintheother.

Ournextbusinessistolookatthegeneralcharacterofthesefossilremains,anditisasubjectwhichitwillberequisitetoconsidercarefully;andthefirstpointforusistoexaminehowmuchtheextinct'Flora'and'Fauna'asa'whole'--disregardingaltogetherthe'succession'oftheirconstituents,ofwhichIshallspeakafterwards--differfromthe'Flora'and'Fauna'ofthepresentday;--how

fartheydifferinwhatwe'do'knowaboutthem,leavingaltogetheroutofconsiderationspeculationsbaseduponwhatwe'donot'know.

Istronglyimaginethatifitwerenotforthepeculiarappearancethatfossilisedanimalshave,anyofyoumightreadilywalkthroughamuseumwhichcontainsfossilremainsmixedupwiththoseofthepresentformsoflife,andIdoubtverymuchwhetheryouruninstructedeyeswouldleadyoutoseeanyvastorwonderfuldifferencebetweenthetwo.Ifyoulookedclosely,youwouldnotice,inthefirstplace,agreatmanythingsverylikeanimalswithwhichyouareacquaintednow:youwouldseedifferencesofshapeandproportion,butonthewholeaclosesimilarity.

IexplainedwhatImeantbyORDERStheotherday,whenIdescribedtheanimalkingdomasbeingdividedinsub-kingdoms,classesandorders.Ifyoudividetheanimalkingdomintoorders,youwillfindthatthereareaboutonehundredandtwenty.Thenumbermayvaryononesideortheother,butthisisafairestimate.Thatisthesumtotaloftheordersofalltheanimalswhichweknownow,andwhichhavebeenknowninpasttimes,andleftremainsbehind.

Now,howmanyofthoseareabsolutelyextinct?Thatistosay,howmanyoftheseordersofanimalshavelivedataformerperiodoftheworld's


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history,buthaveatpresentnorepresentatives?ThatisthesenseinwhichImeanttousetheword"extinct."Imeanthatthoseanimalsdidliveonthisearthatonetime,buthaveleftnooneoftheirkindwithusatthepresentmoment.Sothatestimatingthenumberofextinctanimalsisasortofwayofcomparingthepastcreationasawholewiththepresentasawhole.Amongthemammaliaandbirdstherearenoneextinct;butwhenwecometothereptilesthereisamostwonderfulthing:outoftheeightorders,orthereabouts,whichyoucanmakeamongreptiles,one-halfareextinct.Thesediagramsoftheplesiosaurus,theichthyosaurus,thepterodactyle,giveyouanotionofsomeoftheseextinctreptiles.Andhereisacastofthepterodactyleandbonesoftheichthyosaurusandtheplesiosaurus,justasfreshasifithadbeenrecentlydugupinachurchyard.Thus,inthereptileclass,therearenolessthanhalfoftheorderswhichareabsolutelyextinct.Ifweturntothe'Amphibia',therewasoneextinctorder,theLabyrinthodonts,typifiedbythelargesalamander-likebeastshowninthisdiagram.

Noorderoffishesisknowntobeextinct.Everyfishthatwefindinthestrata--towhichIhavebeenreferring--canbeidentifiedandplacedinoneoftheorderswhichexistatthepresentday.Thereisnotknowntobeasingleordinalformofinsectextinct.Thereareonlytwoordersextinctamongthe'Crustacea'.Thereisnotknowntobeanextinctorderofthesecreatures,theparasiticandotherworms;buttherearetwo,nottosaythree,absolutelyextinctordersofthisclass,the

'Echinodermata';outofalltheordersofthe'Coelenterata'and'Protozoa'onlyone,theRugoseCorals.

Sothat,yousee,outofsomewhereabout120ordersofanimals,takingthemaltogether,youwillnot,attheoutsideestimate,findabovetenoradozenextinct.Summingupalltheordersofanimalswhichhaveleftremainsbehindthem,youwillnotfindabovetenoradozenwhichcannotbearrangedwiththoseofthepresentday;thatistosay,thatthedifferencedoesnotamounttomuchmorethantenpercent.:andtheproportionofextinctordersofplantsisstillsmaller.Ithinkthatthatisaveryastounding,amostastonishingfact,seeingtheenormousepochsoftimewhichhaveelapsedduringtheconstitutionofthesurfaceoftheearthasitatpresentexists;itis,indeed,amostastounding

thingthattheproportionofextinctordinaltypesshouldbesoexceedinglysmall.

Butnow,thereisanotherpointofviewinwhichwemustlookatthispastcreation.Supposethatweweretosinkaverticalpitthroughthefloorbeneathus,andthatIcouldsucceedinmakingasectionrightthroughinthedirectionofNewZealand,IshouldfindineachofthedifferentbedsthroughwhichIpassedtheremainsofanimalswhichIshouldfindinthatstratumandnotintheothers.First,Ishouldcomeuponbedsofgravelordriftcontainingthebonesoflargeanimals,suchastheelephant,rhinoceros,andcavetiger.RathercuriousthingstofallacrossinPiccadilly!IfIshoulddiglowerstill,IshouldcomeuponabedofwhatwecalltheLondonclay,andinthis,asyouwillsee

inourgalleriesupstairs,arefoundremainsofstrangecattle,remainsofturtles,palms,andlargetropicalfruits;withshell-fishsuchasyouseethelikeofnowonlyintropicalregions.IfIwentbelowthat,Ishouldcomeuponthechalk,andthereIshouldfindsomethingaltogetherdifferent,theremainsofichthyosauriandpterodactyles,andammonites,andsoforth.

IdonotknowwhatMr.GodwinAustinwouldsaycomesnext,butprobablyrockscontainingmoreammonites,andmoreichthyosauriandplesiosauri,withavastnumberofotherthings;andunderthatIshouldmeetwith


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yetolderrocks,containingnumbersofstrangeshellsandfishes;andinthuspassingfromthesurfacetothelowestdepthsoftheearth'scrust,theformsofanimallifeandvegetablelifewhichIshouldmeetwithinthesuccessivebedswould,lookingatthembroadly,bethemoredifferentthefurtherthatIwentdown.Or,inotherwords,inasmuchaswestartedwiththeclearprinciple,thatinaseriesofnaturally-disposedmudbedsthelowestaretheoldest,weshouldcometothisresult,thatthefurtherwegobackintimethemoredifferenceexistsbetweentheanimalandvegetablelifeofanepochandthatwhichnowexists.ThatwastheconclusiontowhichIwishedtobringyouattheendofthisLecture.

EndofThePastConditionofOrganicNature.

***

THEMETHODBYWHICHTHECAUSESOFTHEPRESENTANDPASTCONDITIONSOFORGANICNATUREARETOBEDISCOVERED.--THEORIGINATIONOFLIVINGBEINGS.

InthetwoprecedinglecturesIhaveendeavouredtoindicatetoyoutheextentofthesubject-matteroftheinquiryuponwhichweareengaged;andnow,havingthusacquiredsomeconceptionofthePastandPresentphenomenaofOrganicNature,Imustnowturntothatwhichconstitutes

thegreatproblemwhichwehavesetbeforeourselves;--Imean,thequestionofwhatknowledgewehaveofthecausesofthesephenomenaoforganicnature,andhowsuchknowledgeisobtainable.

Here,onthethresholdoftheinquiry,anobjectionmeetsus.Thereareintheworldanumberofextremelyworthy,well-meaningpersons,whosejudgmentsandopinionsareentitledtotheutmostrespectonaccountoftheirsincerity,whoareofopinionthatVitalPhenomena,andespeciallyallquestionsrelatingtotheoriginofvitalphenomena,arequestionsquiteapartfromtheordinaryrunofinquiry,andare,bytheirverynature,placedoutofourreach.Theysaythatallthesephenomenaoriginatedmiraculously,orinsomewaytotallydifferentfromtheordinarycourseofnature,andthatthereforetheyconceiveittobe

futile,nottosaypresumptuous,toattempttoinquireintothem.

Tosuchsincereandearnestpersons,Iwouldonlysay,thataquestionofthiskindisnottobeshelvedupontheoreticalorspeculativegrounds.YoumayrememberthestoryoftheSophistwhodemonstratedtoDiogenesinthemostcompleteandsatisfactorymannerthathecouldnotwalk;that,infact,allmotionwasanimpossibility;andthatDiogenesrefutedhimbysimplygettingupandwalkingroundhistub.So,inthesameway,themanofsciencerepliestoobjectionsofthiskind,bysimplygettingupandwalkingonward,andshowingwhatsciencehasdoneandisdoing--bypointingtothatimmensemassoffactswhichhavebeenascertainedandsystematizedundertheformsofthegreatdoctrinesofMorphology,ofDevelopment,ofDistribution,andthelike.Heseesan

enormousmassoffactsandlawsrelatingtoorganicbeings,whichstandonthesamegoodsoundfoundationaseveryothernaturallaw;andtherefore,withthismassoffactsandlawsbeforeus,therefore,seeingthat,asfarasorganicmattershavehithertobeenaccessibleandstudied,theyhaveshownthemselvescapableofyieldingtoscientificinvestigation,wemayacceptthisasproofthatorderandlawreignthereaswellasintherestofnature;andthemanofsciencesaysnothingtoobjectorsofthissort,butsupposesthatwecanandshallwalktoaknowledgeoftheoriginoforganicnature,inthesamewaythatwehavewalkedtoaknowledgeofthelawsandprinciplesofthe


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inorganicworld.

Butthereareobjectorswhosaythesamefromignoranceandill-will.TosuchIwouldreplythattheobjectioncomesillfromthem,andthattherealpresumption,Imayalmostsaytherealblasphemy,inthismatter,isintheattempttolimitthatinquiryintothecausesofphenomenawhichisthesourceofallhumanblessings,andfromwhichhassprungallhumanprosperityandprogress;for,afterall,wecanaccomplishcomparativelylittle;thelimitedrangeofourownfacultiesboundsusoneveryside,--thefieldofourpowersofobservationissmallenough,andhewhoendeavourstonarrowthesphereofourinquiriesisonlypursuingacoursethatislikelytoproducethegreatestharmtohisfellow-men.

Butnow,assuming,aswealldo,Ihope,thatthesephenomenaareproperlyaccessibletoinquiry,andsettingoutuponoursearchintothecausesofthephenomenaoforganicnature,or,atanyrate,settingouttodiscoverhowmuchweatpresentknowupontheseabstrusematters,thequestionarisesastowhatistobeourcourseofproceeding,andwhatmethodwemustlaydownforourguidance.Ireplytothatquestion,thatourmethodmustbeexactlythesameasthatwhichispursuedinanyotherscientificinquiry,themethodofscientificinvestigationbeingthesameforallordersoffactsandphenomenawhatsoever.

Imustdwellalittleonthispoint,forIwishyoutoleavethisroomwithaveryclearconvictionthatscientificinvestigationisnot,asmanypeopleseemtosuppose,somekindofmodernblackart.Isaythatyoumighteasilygatherthisimpressionfromthemannerinwhichmanypersonsspeakofscientificinquiry,ortalkaboutinductiveanddeductivephilosophy,ortheprinciplesofthe"Baconianphilosophy."Idoprotestthat,ofthevastnumberofcantsinthisworld,therearenone,tomymind,socontemptibleasthepseudoscientificcantwhichistalkedaboutthe"Baconianphilosophy."

TohearpeopletalkaboutthegreatChancellor--andaverygreatmanhecertainlywas,--youwouldthinkthatitwashewhohadinventedscience,andthattherewasnosuchthingassoundreasoningbeforethetimeof

QueenElizabeth.Ofcourseyousay,thatcannotpossiblybetrue;youperceive,onamoment'sreflection,thatsuchanideaisabsurdlywrong,andyet,sofirmlyrootedisthissortofimpression,--Icannotcallitanidea,orconception,--thethingistooabsurdtobeentertained,--butsocompletelydoesitexistatthebottomofmostmen'sminds,thatthishasbeenamatterofobservationwithmeformanyyearspast.Therearemanymenwho,thoughknowingabsolutelynothingofthesubjectwithwhichtheymaybedealing,wish,nevertheless,todamagetheauthorofsomeviewwithwhichtheythinkfittodisagree.Whattheydo,then,isnottogoandlearnsomethingaboutthesubject,whichonewouldnaturallythinkthebestwayoffairlydealingwithit;buttheyabusetheoriginatoroftheviewtheyquestion,inageneralmanner,andwindupbysayingthat,"Afterall,youknow,theprinciplesandmethodof

thisauthoraretotallyopposedtothecanonsoftheBaconianphilosophy."Theneverybodyapplauds,asamatterofcourse,andagreesthatitmustbeso.Butifyouweretostopthemallinthemiddleoftheirapplause,youwouldprobablyfindthatneitherthespeakernorhisapplauderscouldtellyouhoworinwhatwayitwasso;neithertheonenortheotherhavingtheslightestideaofwhattheymeanwhentheyspeakofthe"Baconianphilosophy."

Youwillunderstand,Ihope,thatIhavenottheslightestdesiretojoinintheoutcryagainsteitherthemorals,theintellect,orthe


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greatgeniusofLordChancellorBacon.Hewasundoubtedlyaverygreatman,letpeoplesaywhattheywillofhim;butnotwithstandingallthathedidforphilosophy,itwouldbeentirelywrongtosupposethatthemethodsofmodernscientificinquiryoriginatedwithhim,orwithhisage;theyoriginatedwiththefirstman,whoeverhewas;andindeedexistedlongbeforehim,formanyoftheessentialprocessesofreasoningareexertedbythehigherorderofbrutesascompletelyandeffectivelyasbyourselves.Weseeinmanyofthebrutecreationtheexerciseofone,atleast,ofthesamepowersofreasoningasthatwhichweourselvesemploy.

Themethodofscientificinvestigationisnothingbuttheexpressionofthenecessarymodeofworkingofthehumanmind.Itissimplythemodeatwhichallphenomenaarereasonedabout,renderedpreciseandexact.Thereisnomoredifference,butthereisjustthesamekindofdifference,betweenthementaloperationsofamanofscienceandthoseofanordinaryperson,asthereisbetweentheoperationsandmethodsofabakerorofabutcherweighingouthisgoodsincommonscales,andtheoperationsofachemistinperformingadifficultandcomplexanalysisbymeansofhisbalanceandfinely-graduatedweights.Itisnotthattheactionofthescalesintheonecase,andthebalanceintheother,differintheprinciplesoftheirconstructionormannerofworking;butthebeamofoneissetonaninfinitelyfineraxisthantheother,andofcourseturnsbytheadditionofamuchsmallerweight.

Youwillunderstandthisbetter,perhaps,ifIgiveyousomefamiliarexample.Youhaveallhearditrepeated,Idaresay,thatmenofscienceworkbymeansofInductionandDeduction,andthatbythehelpoftheseoperations,they,inasortofsense,wringfromNaturecertainotherthings,whicharecalledNaturalLaws,andCauses,andthatoutofthese,bysomecunningskilloftheirown,theybuildupHypothesesandTheories.Anditisimaginedbymany,thattheoperationsofthecommonmindcanbebynomeanscomparedwiththeseprocesses,andthattheyhavetobeacquiredbyasortofspecialapprenticeshiptothecraft.Tohearalltheselargewords,youwouldthinkthatthemindofamanofsciencemustbeconstituteddifferentlyfromthatofhisfellowmen;butifyouwillnotbefrightenedbyterms,youwilldiscoverthatyouare

quitewrong,andthatalltheseterribleapparatusarebeingusedbyyourselveseverydayandeveryhourofyourlives.

Thereisawell-knownincidentinoneofMoliere'splays,wheretheauthormakestheheroexpressunboundeddelightonbeingtoldthathehadbeentalkingproseduringthewholeofhislife.Inthesameway,Itrust,thatyouwilltakecomfort,andbedelightedwithyourselves,onthediscoverythatyouhavebeenactingontheprinciplesofinductiveanddeductivephilosophyduringthesameperiod.Probablythereisnotoneherewhohasnotinthecourseofthedayhadoccasiontosetinmotionacomplextrainofreasoning,oftheverysamekind,thoughdifferingofcourseindegree,asthatwhichascientificmangoesthroughintracingthecausesofnaturalphenomena.

Averytrivialcircumstancewillservetoexemplifythis.Supposeyougointoafruiterer'sshop,wantinganapple,--youtakeupone,and,onbitingit,youfinditissour;youlookatit,andseethatitishardandgreen.Youtakeupanotherone,andthattooishard,green,andsour.Theshopmanoffersyouathird;but,beforebitingit,youexamineit,andfindthatitishardandgreen,andyouimmediatelysaythatyouwillnothaveit,asitmustbesour,likethosethatyouhavealreadytried.


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Nothingcanbemoresimplethanthat,youthink;butifyouwilltakethetroubletoanalyzeandtraceoutintoitslogicalelementswhathasbeendonebythemind,youwillbegreatlysurprised.Inthefirstplace,youhaveperformedtheoperationofINDUCTION.Youfoundthat,intwoexperiences,hardnessandgreennessinapplesgotogetherwithsourness.Itwassointhefirstcase,anditwasconfirmedbythesecond.True,itisaverysmallbasis,butstillitisenoughtomakeaninductionfrom;yougeneralizethefacts,andyouexpecttofindsournessinappleswhereyougethardnessandgreenness.Youfounduponthatagenerallaw,thatallhardandgreenapplesaresour;andthat,sofarasitgoes,isaperfectinduction.Well,havinggotyournaturallawinthisway,whenyouareofferedanotherapplewhichyoufindishardandgreen,yousay,"Allhardandgreenapplesaresour;thisappleishardandgreen,thereforethisappleissour."Thattrainofreasoningiswhatlogicianscallasyllogism,andhasallitsvariouspartsandterms,--itsmajorpremiss,itsminorpremiss,anditsconclusion.And,bythehelpoffurtherreasoning,which,ifdrawnout,wouldhavetobeexhibitedintwoorthreeothersyllogisms,youarriveatyourfinaldetermination,"Iwillnothavethatapple."Sothat,yousee,youhave,inthefirstplace,establishedalawbyInduction,anduponthatyouhavefoundedaDeduction,andreasonedoutthespecialconclusionoftheparticularcase.Wellnow,suppose,havinggotyourlaw,thatatsometimeafterwards,youarediscussingthequalitiesofappleswithafriend:youwillsaytohim,"Itisaverycurious

thing,--butIfindthatallhardandgreenapplesaresour!"Yourfriendsaystoyou,"Buthowdoyouknowthat?"Youatoncereply,"Oh,becauseIhavetrieditoverandoveragain,andhavealwaysfoundthemtobeso."Well.ifweweretalkingscienceinsteadofcommonsense,weshouldcallthatanExperimentalVerification.And,ifstillopposed,yougofurther,andsay,"IhaveheardfromthepeopleinSomersetshireandDevonshire,wherealargenumberofapplesaregrown,thattheyhaveobservedthesamething.ItisalsofoundtobethecaseinNormandy,andinNorthAmerica.Inshort,Ifindittobetheuniversalexperienceofmankindwhereverattentionhasbeendirectedtothesubject."Whereupon,yourfriend,unlessheisaveryunreasonableman,agreeswithyou,andisconvincedthatyouarequiterightintheconclusionyouhavedrawn.Hebelieves,althoughperhapshedoesnotknowhe

believesit,thatthemoreextensiveVerificationsare,--thatthemorefrequentlyexperimentshavebeenmade,andresultsofthesamekindarrivedat,--thatthemorevariedtheconditionsunderwhichthesameresultshavebeenattained,themorecertainistheultimateconclusion,andhedisputesthequestionnofurther.Heseesthattheexperimenthasbeentriedunderallsortsofconditions,astotime,place,andpeople,withthesameresult;andhesayswithyou,therefore,thatthelawyouhavelaiddownmustbeagoodone,andhemustbelieveit.

Insciencewedothesamething;--thephilosopherexercisespreciselythesamefaculties,thoughinamuchmoredelicatemanner.Inscientificinquiryitbecomesamatterofdutytoexposeasupposedlawtoeverypossiblekindofverification,andtotakecare,moreover,thatthisis

doneintentionally,andnotlefttoamereaccident,asinthecaseoftheapples.Andinscience,asincommonlife,ourconfidenceinalawisinexactproportiontotheabsenceofvariationintheresultofourexperimentalverifications.Forinstance,ifyouletgoyourgraspofanarticleyoumayhaveinyourhand,itwillimmediatelyfalltotheground.Thatisaverycommonverificationofoneofthebestestablishedlawsofnature--thatofgravitation.Themethodbywhichmenofscienceestablishtheexistenceofthatlawisexactlythesameasthatbywhichwehaveestablishedthetrivialpropositionaboutthesournessofhardandgreenapples.Butwebelieveitinsuchan


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extensive,thorough,andunhesitatingmannerbecausetheuniversalexperienceofmankindverifiesit,andwecanverifyitourselvesatanytime;andthatisthestrongestpossiblefoundationonwhichanynaturallawcanrest.

Somuchbywayofproofthatthemethodofestablishinglawsinscienceisexactlythesameasthatpursuedincommonlife.Letusnowturntoanothermatter(thoughreallyitisbutanotherphaseofthesamequestion),andthatis,themethodbywhich,fromtherelationsofcertainphenomena,weprovethatsomestandinthepositionofcausestowardstheothers.

Iwanttoputthecaseclearlybeforeyou,andIwillthereforeshowyouwhatImeanbyanotherfamiliarexample.Iwillsupposethatoneofyou,oncomingdowninthemorningtotheparlourofyourhouse,findsthatatea-potandsomespoonswhichhadbeenleftintheroomonthepreviouseveningaregone,--thewindowisopen,andyouobservethemarkofadirtyhandonthewindow-frame,andperhaps,inadditiontothat,younoticetheimpressofahob-nailedshoeonthegraveloutside.Allthesephenomenahavestruckyourattentioninstantly,andbeforetwominuteshavepassedyousay,"Oh,somebodyhasbrokenopenthewindow,enteredtheroom,andrunoffwiththespoonsandthetea-pot!"Thatspeechisoutofyourmouthinamoment.Andyouwillprobablyadd,"Iknowtherehas;Iamquitesureofit!"Youmeantosayexactlywhatyouknow;but

inrealitywhatyouhavesaidhasbeentheexpressionofwhatis,inallessentialparticulars,anHypothesis.Youdonot'know'itatall;itisnothingbutanhypothesisrapidlyframedinyourownmind!Anditisanhypothesisfoundedonalongtrainofinductionsanddeductions.

Whatarethoseinductionsanddeductions,andhowhaveyougotatthishypothesis?Youhaveobserved,inthefirstplace,thatthewindowisopen;butbyatrainofreasoninginvolvingmanyInductionsandDeductions,youhaveprobablyarrivedlongbeforeattheGeneralLaw--andaverygoodoneitis--thatwindowsdonotopenofthemselves;andyouthereforeconcludethatsomethinghasopenedthewindow.Asecondgenerallawthatyouhavearrivedatinthesamewayis,thattea-potsandspoonsdonotgooutofawindowspontaneously,andyouare

satisfiedthat,astheyarenotnowwhereyouleftthem,theyhavebeenremoved.Inthethirdplace,youlookatthemarksonthewindow-sill,andtheshoemarksoutside,andyousaythatinallpreviousexperiencetheformerkindofmarkhasneverbeenproducedbyanythingelsebutthehandofahumanbeing;andthesameexperienceshowsthatnootheranimalbutmanatpresentwearsshoeswithhob-nailsonthemsuchaswouldproducethemarksinthegravel.Idonotknow,evenifwecoulddiscoveranyofthose"missinglinks"thataretalkedabout,thattheywouldhelpustoanyotherconclusion!Atanyratethelawwhichstatesourpresentexperienceisstrongenoughformypresentpurpose.--Younextreachtheconclusion,thatasthesekindsofmarkshavenotbeenleftbyanyotheranimalsthanmen,orareliabletobeformedinanyotherwaythanbyaman'shandandshoe,themarksinquestionhavebeen

formedbyamaninthatway.Youhave,further,agenerallaw,foundedonobservationandexperience,andthat,too,is,Iamsorrytosay,averyuniversalandunimpeachableone,--thatsomemenarethieves;andyouassumeatoncefromallthesepremisses--andthatiswhatconstitutesyourhypothesis--thatthemanwhomadethemarksoutsideandonthewindow-sill,openedthewindow,gotintotheroom,andstoleyourtea-potandspoons.Youhavenowarrivedata'VeraCausa';--youhaveassumedaCausewhichitisplainiscompetenttoproduceallthephenomenayouhaveobserved.Youcanexplainallthesephenomenaonlybythehypothesisofathief.Butthatisahypotheticalconclusion,ofthe


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justiceofwhichyouhavenoabsoluteproofatall;itisonlyrenderedhighlyprobablebyaseriesofinductiveanddeductivereasonings.

Isupposeyourfirstaction,assumingthatyouareamanofordinarycommonsense,andthatyouhaveestablishedthishypothesistoyourownsatisfaction,willverylikelybetogooffforthepolice,andsetthemonthetrackoftheburglar,withtheviewtotherecoveryofyourproperty.Butjustasyouarestartingwiththisobject,somepersoncomesin,andonlearningwhatyouareabout,says,"Mygoodfriend,youaregoingonagreatdealtoofast.Howdoyouknowthatthemanwhoreallymadethemarkstookthespoons?Itmighthavebeenamonkeythattookthem,andthemanmayhavemerelylookedinafterwards."Youwouldprobablyreply,"Well,thatisallverywell,butyouseeitiscontrarytoallexperienceofthewaytea-potsandspoonsareabstracted;sothat,atanyrate,yourhypothesisislessprobablethanmine."Whileyouaretalkingthethingoverinthisway,anotherfriendarrives,oneofthatgoodkindofpeoplethatIwastalkingofalittlewhileago.Andhemightsay,"Oh,mydearsir,youarecertainlygoingonagreatdealtoofast.Youaremostpresumptuous.Youadmitthatalltheseoccurrencestookplacewhenyouwerefastasleep,atatimewhenyoucouldnotpossiblyhaveknownanythingaboutwhatwastakingplace.HowdoyouknowthatthelawsofNaturearenotsuspendedduringthenight?Itmaybethattherehasbeensomekindofsupernaturalinterferenceinthiscase."Inpointoffact,hedeclaresthatyourhypothesisisoneof

whichyoucannotatalldemonstratethetruth,andthatyouarebynomeanssurethatthelawsofNaturearethesamewhenyouareasleepaswhenyouareawake.

Well,now,youcannotatthemomentanswerthatkindofreasoning.Youfeelthatyourworthyfriendhasyousomewhatatadisadvantage.Youwillfeelperfectlyconvincedinyourownmind,however,thatyouarequiteright,andyousaytohim,"Mygoodfriend,Icanonlybeguidedbythenaturalprobabilitiesofthecase,andifyouwillbekindenoughtostandasideandpermitmetopass,Iwillgoandfetchthepolice."Well,wewillsupposethatyourjourneyissuccessful,andthatbygoodluckyoumeetwithapoliceman;thateventuallytheburglarisfoundwithyourpropertyonhisperson,andthemarkscorrespondtohishand

andtohisboots.Probablyanyjurywouldconsiderthosefactsaverygoodexperimentalverificationofyourhypothesis,touchingthecauseoftheabnormalphenomenaobservedinyourparlour,andwouldactaccordingly.

Now,inthissupposititiouscase,Ihavetakenphenomenaofaverycommonkind,inorderthatyoumightseewhatarethedifferentstepsinanordinaryprocessofreasoning,ifyouwillonlytakethetroubletoanalyseitcarefully.AlltheoperationsIhavedescribed,youwillsee,areinvolvedinthemindofanymanofsenseinleadinghimtoaconclusionastothecourseheshouldtakeinordertomakegoodarobberyandpunishtheoffender.Isaythatyouareled,inthatcase,toyourconclusionbyexactlythesametrainofreasoningasthatwhich

amanofsciencepursueswhenheisendeavouringtodiscovertheoriginandlawsofthemostoccultphenomena.Theprocessis,andalwaysmustbe,thesame;andpreciselythesamemodeofreasoningwasemployedbyNewtonandLaplaceintheirendeavourstodiscoveranddefinethecausesofthemovementsoftheheavenlybodies,asyou,withyourowncommonsense,wouldemploytodetectaburglar.Theonlydifferenceis,thatthenatureoftheinquirybeingmoreabstruse,everystephastobemostcarefullywatched,sothattheremaynotbeasinglecrackorflawinyourhypothesis.Aflaworcrackinmanyofthehypothesesofdailylifemaybeoflittleornomomentasaffectingthegeneralcorrectnessof


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theconclusionsatwhichwemayarrive;but,inascientificinquiry,afallacy,greatorsmall,isalwaysofimportance,andissuretobeconstantlyproductiveofmischievous,ifnotfatalresults.

Donotallowyourselvestobemisledbythecommonnotionthatanhypothesisisuntrustworthysimplybecauseitisanhypothesis.Itisoftenurged,inrespecttosomescientificconclusion,that,afterall,itisonlyanhypothesis.Butwhatmorehavewetoguideusinnine-tenthsofthemostimportantaffairsofdailylifethanhypotheses,andoftenveryill-basedones?Sothatinscience,wheretheevidenceofanhypothesisissubjectedtothemostrigidexamination,wemayrightlypursuethesamecourse.Youmayhavehypothesesandhypotheses.Amanmaysay,ifhelikes,thatthemoonismadeofgreencheese:thatisanhypothesis.Butanotherman,whohasdevotedagreatdealoftimeandattentiontothesubject,andavailedhimselfofthemostpowerfultelescopesandtheresultsoftheobservationsofothers,declaresthatinhisopinionitisprobablycomposedofmaterialsverysimilartothoseofwhichourownearthismadeup:andthatisalsoonlyanhypothesis.ButIneednottellyouthatthereisanenormousdifferenceinthevalueofthetwohypotheses.Thatonewhichisbasedonsoundscientificknowledgeissuretohaveacorrespondingvalue;andthatwhichisamerehastyrandomguessislikelytohavebutlittlevalue.EverygreatstepinourprogressindiscoveringcauseshasbeenmadeinexactlythesamewayasthatwhichIhavedetailedtoyou.Aperson

observingtheoccurrenceofcertainfactsandphenomenaasks,naturallyenough,whatprocess,whatkindofoperationknowntooccurinnatureappliedtotheparticularcase,willunravelandexplainthemystery?Henceyouhavethescientifichypothesis;anditsvaluewillbeproportionatetothecareandcompletenesswithwhichitsbasishadbeentestedandverified.Itisinthesemattersasinthecommonestaffairsofpracticallife:theguessofthefoolwillbefolly,whiletheguessofthewisemanwillcontainwisdom.Inallcases,youseethatthevalueoftheresultdependsonthepatienceandfaithfulnesswithwhichtheinvestigatorappliestohishypothesiseverypossiblekindofverification.

IdaresayImayhavetoreturntothispointby-and-by;buthaving

dealtthusfarwithourlogicalmethods,Imustnowturntosomethingwhich,perhaps,youmayconsidermoreinteresting,or,atanyrate,moretangible.Butinrealitytherearebutfewthingsthatcanbemoreimportantforyoutounderstandthanthementalprocessesandthemeansbywhichweobtainscientificconclusionsandtheories.*([Footnote]*ThosewhowishtostudyfullythedoctrinesofwhichIhaveendeavouredtogivesomeroughandreadyillus

lectures and essays by huxley, thomas henry, 1825-1895

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