Thusitwouldappeartobedemonstrable，that，notwithstandingthegreatchangewhichisexhibitedbytheanimalpopulationoftheworldasawhole，certaintypeshavepersistedcomparativelywithoutalteration，andthequestionarises，Whatbearinghavesuchfactsastheseonournotionsofthehistoryoflifethroughgeologicaltime？Theanswertothisquestionwouldseemtodependontheviewwetakerespectingtheoriginofspeciesingeneral。Ifweassumethateveryspeciesofanimalandofplantwasformedbyadistinctactofcreativepower，andifthespecieswhichhaveincessantlysucceededoneanotherwereplacedupontheglobebytheseseparateacts，thentheexistenceofpersistenttypesissimplyanunintelligibleirregularity。Suchassumption，however，isasunsupportedbytraditionorbyRevelationasitisopposedbytheanalogyoftherestoftheoperationsofnature；andthosewhoimaginethat，byadoptinganysuchhypothesis，theyarestrengtheningthehandsoftheadvocatesoftheletteroftheMosaicaccount，aresimplymistaken。If，ontheotherhand，weadoptthathypothesistowhichalonethestudyofphysiologylendsanysupport——thathypothesiswhich，havingstruggledbeyondthereachofthosefatalsupporters，theTelliamedsandVestigiarians，whosonearlycauseditssuffocationbywindinearlyinfancy，isnowwinningatleasttheprovisionalassentofallthebestthinkersoftheday——thehypothesisthattheformsorspeciesoflivingbeings，asweknowthem，havebeenproducedbythegradualmodificationofpre-existingspecies——thentheexistenceofpersistenttypesseemstoteachusmuch。Justasasmallportionofagreatcurveappearsstraight，theapparentabsenceofchangeindirectionofthelinebeingtheexponentofthevastextentofthewhole，inproportiontothepartwesee；so，ifitbetruethatalllivingspeciesaretheresultofthemodificationofotherandsimplerforms，theexistenceoftheselittlealteredpersistenttypes，rangingthroughallgeologicaltime，mustindicatethattheyarebutthefinaltermsofanenormousseriesofmodifications，whichhadtheirbeinginthegreatlapseofpregeologictime，andarenowperhapsforeverlost。
Inotherwords，whenrightlystudied，theteachingsofpalaeontologyareatonewiththoseofphysicalgeology。OurfarthestexplorationscarryusbackbutalittlewayabovethemouthofthegreatriverofLife:
whereitarose，andbywhatchannelsthenobletidehasreachedthepointwhenitfirstbreaksuponourview，ishiddenfromus。
TheforegoingpagescontainthesubstanceofalecturedeliveredbeforetheRoyalInstitutionofGreatBritainmanymonthsago，andofcourselongbeforetheappearanceoftheremarkableworkonthe\"OriginofSpecies\"justpublishedbyMr。Darwin，whoarrivesatverysimilarconclusions。Although，inonesense，Imightfairlysaythatmyownviewshavebeenarrivedatindependently，IdonotknowthatIcanclaimanyequitablerighttopropertyinthem；forithaslongbeenmyprivilegetoenjoyMr。Darwin\'sfriendship，andtoprofitbycorrespondingwithhim，andby，tosomeextent，becomingacquaintedwiththeworkingsofhissingularlyoriginalandwell-storedmind。ItwasinconsequenceofmyknowledgeofthegeneraltenoroftheresearchesinwhichMr。Darwinhadbeensolongengaged；becauseIhadthemostcompleteconfidenceinhisperseverance，hisknowledge，and，aboveallthings，hishigh-mindedloveoftruth；and，moreover，becauseIfoundthatthebetterIbecameacquaintedwiththeopinionsofthebestnaturalistsregardingthevexedquestionofspecies，thelessfixedtheyseemedtobe，andthemoreinclinedtheyweretothehypothesisofgradualmodification，thatIventuredtospeakasstronglyasIhavedoneinthefinalparagraphsofmydiscourse。
Thus，mydawhavingsomanyborrowedplumes，IseenoimproprietyinmakingatailtothisbriefpaperbytakinganotherhandfuloffeathersfromMr。Darwin；endeavouringtopointoutinafewwords，infact，what，asIgatherfromtheperusalofhisbook，hisdoctrinesreallyare，andonwhatsortofbasistheyrest。AndIdothisthemorewillingly，asIobservethatalreadythehastiersortofcriticshavebegun，nottoreviewmyfriend\'sbook，buttohowloveritinamannerwhichmusttendgreatlytodistractthepublicmind。
NoonewillbebettersatisfiedthanItoseeMr。Darwin\'sbookrefuted，ifanypersonbecompetenttoperformthatfeat；butIwouldsuggestthatrefutationisretarded，notaided，bymeresarcasticmisrepresentation。Everyonewhohasstudiedcattle-breeding，orturnedpigeon-fancier，or\"pomologist，\"musthavebeenstruckbytheextrememodifiabilityorplasticityofthosekindsofanimalsandplantswhichhavebeensubjectedtosuchartificialconditionsasareimposedbydomestication。Breedsofdogsaremoredifferentfromoneanotherthanarethedogandthewolf；andthepurelyartificialracesofpigeons，iftheiroriginwereunknown，wouldmostassuredlybereckonedbynaturalistsasdistinctspeciesandevengenera。
Thesebreedsarealwaysproducedinthesameway。Thebreederselectsapair，oneorother，orboth，ofwhichpresentanindicationofthepeculiarityhewishestoperpetuate，andthenselectsfromtheoffspringofthemthosewhicharemostcharacteristic，rejectingtheothers。Fromtheselectedoffspringhebreedsagain，and，takingthesameprecautionsasbefore，repeatstheprocessuntilhehasobtainedtheprecisedegreeofdivergencefromtheprimitivetypeatwhichheaimed。
Ifhenowbreedsfromthevarietythusestablishedforsomegenerations，takingcarealwaystokeepthestockpure，thetendencytoproducethisparticularvarietybecomesmoreandmorestronglyhereditary；anditdoesnotappearthatthereisanylimittothepersistencyoftheracethusdeveloped。
MenlikeLamarck，apprehendingthesefacts，andknowingthatvarietiescomparabletothoseproducedbythebreederareabundantlyfoundinnature，andfindingitimpossibletodiscriminateinsomecasesbetweenvarietiesandtruespecies，couldhardlyfailtodivinethepossibilitythatspecieseventhemostdistinctwere，afterall，onlyexceedinglypersistentvarieties，andthattheyhadarisenbythemodificationofsomecommonstock，justasitiswithgoodreasonbelievedthatturnspitsandgreyhounds，carrierandtumblerpigeons，havearisen。
Buttherewasalinkwantingtocompletetheparallel。Whereinnaturewastheanalogueofthebreedertobefound？Howcouldthatoperationofselection，whichishisessentialfunction，becarriedoutbymerenaturalagencies？Lamarckdidnotvaluethisproblem；neitherdidheadmithisimpotencetosolveit；butheguessedasolution。Now，guessinginscienceisaveryhazardousproceeding，andLamarck\'sreputationhassufferedwoefullyfortheabsurditiesintowhichhisbaselesssuppositionsledhim。
Lamarck\'sconjectures，equippedwithanewhatandstick，asSirWalterScottwaswonttosayofanoldstoryrenovated，formedthefoundationofthebiologicalspeculationsofthe\'Vestiges\'，aworkwhichhasdonemoreharmtotheprogressofsoundthoughtonthesemattersthananythatcouldbenamed；and，indeed，ImentionitheresimplyforthepurposeofdenyingthatithasanythingincommonwithwhatessentiallycharacterisesMr。Darwin\'swork。
Thepeculiarfeatureofthelatteris，infact，thatitprofessestotelluswhatinnaturetakestheplaceofthebreeder；whatitisthatfavoursthedevelopmentofonevarietyintowhichaspeciesmayrun，andchecksthatofanother；and，finally，showshowthisnaturalselection，asitistermed，maybethephysicalcauseoftheproductionofspeciesbymodification。
ThatwhichtakestheplaceofthebreederandselectorinnatureisDeath。Inamostremarkablechapter，\'OntheStruggleforExistence\'，Mr。Darwindrawsattentiontothemarvellousdestructionoflifewhichisconstantlygoingoninnature。Foreveryspeciesoflivingthing，asforman，\"EineBrescheisteinjederTag。\"——Everyspecieshasitsenemies；everyspecieshastocompetewithothersforthenecessariesofexistence；theweakestgoestothewall，anddeathisthepenaltyinflictedonalllaggardsandstragglers。Everyvarietytowhichaspeciesmaygiveriseiseitherworseorbetteradaptedtosurroundingcircumstancesthanitsparent。Ifworse，itcannotmaintainitselfagainstdeath，andspeedilyvanishesagain。Butifbetteradapted，itmust，soonerorlater，\"improve\"itsprogenitorfromthefaceoftheearth，andtakeitsplace。Ifcircumstanceschange，thevictorwillbesimilarlysupplantedbyitsownprogeny；andthus，bytheoperationofnaturalcauses，unlimitedmodificationmayinthelapseoflongagesoccur。
ForanexplanationofwhatIhaveherecalledvaguely\"surroundingcircumstances，\"andofwhytheycontinuallychange——forampleproofthatthe\"struggleforexistence\"isaverygreatreality，andassuredly\'tends\'toexerttheinfluenceascribedtoit——ImustrefertoMr。Darwin\'sbook。IbelieveIhavestatedfairlythepositionuponwhichhiswholetheorymuststandorfall；anditisnotmypurposetoanticipateafullreviewofhiswork。Ifitcanbeprovedthattheprocessofnaturalselection，operatinguponanyspecies，cangiverisetovarietiesofspeciessodifferentfromoneanotherthatnoneofourtestswilldistinguishthemfromtruespecies，Mr。Darwin\'shypothesisoftheoriginofspecieswilltakeitsplaceamongtheestablishedtheoriesofscience，beitsconsequenceswhatevertheymay。If，ontheotherhand，Mr。Darwinhaserred，eitherinfactorinreasoning，hisfellow-workerswillsoonfindouttheweakpointsinhisdoctrines，andtheirextinctionbysomenearerapproximationtothetruthwillexemplifyhisownprincipleofnaturalselection。
Ineithercasethequestionisonetobesettledonlybythepainstaking，truth-lovinginvestigationofskillednaturalists。Itisthedutyofthegeneralpublictoawaittheresultinpatience；and，aboveallthings，todiscourage，astheywouldanyothercrimes，theattempttoenlisttheprejudicesoftheignorant，ortheuncharitablenessofthebigoted，oneithersideofthecontroversy。