’QuarterlyReview’1849page392。），insomeotherpoints:butthereisnoreasontobelievethatthissplit，theoriginofwhichisunknown，wasintentionallymade;itmaywithmuchmoreprobabilitybeattributedtodifferentbreedershavingattendedtodifferentpoints。Soagain，theBerkshirebreedofswineintheyear1810hadgreatlychangedfromwhatitwasin1780;andsince1810atleasttwodistinctsub—breedshavearisenbearingthesamename。（20/80。H。vonNathusius’Vorstudien……Schweineschadel’1864s140。）Keepinginmindhowrapidlyallanimalsincrease，andthatsomemustbeannuallyslaughteredandsomesavedforbreeding，then，ifthesamebreederduringalongcourseofyearsdeliberatelysettleswhichshallbesavedandwhichshallbekilled，itisalmostinevitablethathisindividualturnofmindwillinfluencethecharacterofhisstock，withouthishavinghadanyintentiontomodifythebreed。
Unconsciousselectioninthestrictestsenseoftheword，thatis，thesavingofthemoreusefulanimalsandtheneglectorslaughterofthelessuseful，withoutanythoughtofthefuture，musthavegoneonoccasionallyfromtheremotestperiodandamongstthemostbarbarousnations。Savagesoftensufferfromfamines，andaresometimesexpelledbywarfromtheirownhomes。Insuchcasesitcanhardlybedoubtedthattheywouldsavetheirmostusefulanimals。
WhentheFuegiansarehardpressedbywant，theykilltheiroldwomenforfoodratherthantheirdogs;for，aswewereassured，"oldwomennouse——dogscatchotters。"Thesamesoundsensewouldsurelyleadthemtopreservetheirmoreusefuldogswhenstillharderpressedbyfamine。Mr。Oldfield，whohasseensomuchoftheaboriginesofAustralia，informsmethat"theyareallverygladtogetaEuropeankangaroodog，andseveralinstanceshavebeenknownofthefatherkillinghisowninfantthatthemothermightsucklethemuch—prizedpuppy。"DifferentkindsofdogswouldbeusefultotheAustralianforhuntingopossumsandkangaroos，andtotheFuegianforcatchingfishandotters;andtheoccasionalpreservationinthetwocountriesofthemostusefulanimalswouldultimatelyleadtotheformationoftwowidelydistinctbreeds。
Withplants，fromtheearliestdawnofcivilisation，thebestvarietywhichwasknownwouldgenerallyhavebeencultivatedateachperiodanditsseedsoccasionallysown;sothattherewillhavebeensomeselectionfromanextremelyremoteperiod，butwithoutanyprefixedstandardofexcellenceorthoughtofthefuture。Weatthepresentdayprofitbyacourseofselectionoccasionallyandunconsciouslycarriedonduringthousandsofyears。ThisisprovedinaninterestingmannerbyOswaldHeer’sresearchesonthelake—
inhabitantsofSwitzerland，asgiveninaformerchapter;forheshowsthatthegrainandseedofourpresentvarietiesofwheat，barley，oats，peas，beans，lentils，andpoppy，exceedinsizethosewhichwerecultivatedinSwitzerlandduringtheNeolithicandBronzeperiods。Theseancientpeople，duringtheNeolithicperiod，possessedalsoacrabconsiderablylargerthanthatnowgrowingwildontheJura。（20/81。SeealsoDr。ChristinRutimeyer’s’Pfahlbauten’1861s。226。）ThepearsdescribedbyPlinywereevidentlyextremelyinferiorinqualitytoourpresentpears。Wecanrealisetheeffectsoflong—continuedselectionandcultivationinanotherway，forwouldanyoneinhissensesexpecttoraiseafirst—rateapplefromtheseedofatrulywildcrab，oralusciousmeltingpearfromthewildpear？AlphonsedeCandolleinformsmethathehaslatelyseenonanancientmosaicatRomearepresentationofthemelon;andastheRotnans，whoweresuchgourmands，aresilentonthisfruit，heinfersthatthemelonhasbeengreatlyamelioratedsincetheclassicalperiod。
Comingtolatertimes，Buffon（20/82。Thepassageisgiven’Bull。Soc。
d’Acclimat。’1858page11。）oncomparingtheflowers，fruit，andvegetableswhichwerethencultivatedwithsomeexcellentdrawingsmadeahundredandfiftyyearspreviously，wasstruckwithsurpriseatthegreatimprovementwhichhadbeeneffected;andremarksthattheseancientflowersandvegetableswouldnowberejected，notonlybyafloristbutbyavillagegardener。SincethetimeofBuffontheworkofimprovementhassteadilyandrapidlygoneon。
Everyfloristwhocomparesourpresentflowerswiththosefiguredinbookspublishednotlongsince，isastonishedatthechange。Awell—knownamateur（20/83。’JournalofHorticulture’1862page394。），inspeakingofthevarietiesofPelargoniumraisedbyMr。Garthonlytwenty—twoyearsbefore，remarks，"Whataragetheyexcited:surelywehadattainedperfection，itwassaid;andnownotoneoftheflowersofthosedayswillbelookedat。Butnonethelessisthedebtofgratitudewhichweowetothosewhosawwhatwastobedone，anddidit。"Mr。Paul，thewell—knownhorticulturist，inwritingofthesameflower（20/84。’Gardener’sChronicle’1857page85。），saysherememberswhenyoungbeingdelightedwiththeportraitsinSweet’swork;"butwhataretheyinpointofbeautycomparedwiththePelargoniumsofthisday？Hereagainnaturedidnotadvancebyleaps;theimprovementwasgradual，andifwehadneglectedthoseverygradualadvances，wemusthaveforegonethepresentgrandresults。"Howwellthispracticalhorticulturistappreciatesandillustratesthegradualandaccumulativeforceofselection！TheDahliahasadvancedinbeautyinalikemanner;thelineofimprovementbeingguidedbyfashion，andbythesuccessivemodificationswhichtheflowerslowlyunderwent。（20/85。SeeMr。Wildman’saddresstotheFloricult。Soc。in’Gardener’sChronicle’1843
page86。）Asteadyandgradualchangehasbeennoticedinmanyotherflowers:
thusanoldflorist（20/86。’JournalofHorticulture’October24，1865page239。），afterdescribingtheleadingvarietiesofthePinkwhichweregrownin1813adds，"thepinksofthosedayswouldnowbescarcelygrownasborder—
flowers。"Theimprovementofsomanyflowersandthenumberofthevarietieswhichhavebeenraisedisallthemorestrikingwhenwehearthattheearliestknownflower—gardeninEurope，namelyatPadua，datesonlyfromtheyear1545。
（20/87。Prescott’Hist。ofMexico’volume2page61。）
EFFECTSOFSELECTION，ASSHOWNBYTHEPARTSMOSTVALUEDBYMANPRESENTINGTHE
GREATESTAMOUNTOFDIFFERENCE。
Thepoweroflong—continuedselection，whethermethodicalorunconscious，orbothcombined，iswellshowninageneralway，namely，bythecomparisonofthedifferencesbetweenthevarietiesofdistinctspecies，whicharevaluedfordifferentparts，suchasfortheleaves，orstems，ortubers，theseed，orfruit，orflowers。Whateverpartmanvaluesmost，thatpartwillbefoundtopresentthegreatestamountofdifference。Withtreescultivatedfortheirfruit，Sageretremarksthatthefruitislargerthanintheparent—species，whilstwiththosecultivatedfortheseed，aswithnuts，walnuts，almonds，chestnuts，etc。，itistheseeditselfwhichislarger;andheaccountsforthisfactbythefruitintheonecase，andbytheseedintheother，havingbeencarefullyattendedtoandselectedduringmanyages。Gallesiohasmadethesameobservation。Godroninsistsonthediversityofthetuberinthepotato，ofthebulbintheonion，andofthefruitinthemelon;andontheclosesimilarityoftheotherpartsinthesesameplants。（20/88。Sagaret’PomologiePhysiologique’1830page47;Gallesio’TeoriadellaRiproduzione’
1816page88;Godron’Del’Espece’1859tome2pages63，67，70。InmytenthandeleventhchaptersIhavegivendetailsonthepotato;andIcanconfirmsimilarremarkswithrespecttotheonion。IhavealsoshownhowfarNaudinconcursinregardtothevarietiesofthemelon。）
Inordertojudgehowfarmyownimpressiononthissubjectwascorrect，I
cultivatednumerousvarietiesofthesamespeciesclosetooneanother。Thecomparisonoftheamountofdifferencebetweenwidelydifferentorgansisnecessarilyvague;Iwillthereforegivetheresultsinonlyafewcases。Wehavepreviouslyseenintheninthchapterhowgreatlythevarietiesofthecabbagedifferintheirfoliageandstems，whicharetheselectedparts，andhowcloselytheyresembleoneanotherintheirflowers，capsules，andseeds。
Insevenvarietiesoftheradish，therootsdifferedgreatlyincolourandshape，butnodifferencewhatevercouldbedetectedintheirfoliage，flowers，orseeds。Nowwhatacontrastispresented，ifwecomparetheflowersofthevarietiesofthesetwoplantswiththoseofanyspeciescultivatedinourflower—gardensforornament;orifwecomparetheirseedswiththoseofthevarietiesofmaize，peas，beans，etc。，whicharevaluedandcultivatedfortheirseeds。Intheninthchapteritwasshownthatthevarietiesofthepeadifferbutlittleexceptinthetallnessoftheplant，moderatelyintheshapeofthepod，andgreatlyinthepeaitself，andtheseareallselectedpoints。
Thevarieties，however，ofthePoissansparchemindiffermuchmoreintheirpods，andtheseareeatenandvalued。Icultivatedtwelvevarietiesofthecommonbean;onealone，theDwarfFan，differedconsiderablyingeneralappearance;twodifferedinthecolouroftheirflowers，onebeinganalbino，andtheotherbeingwhollyinsteadofpartiallypurple;severaldifferedconsiderablyintheshapeandsizeofthepod，butfarmoreinthebeanitself，andthisisthevaluedandselectedpart。Toker’sbean，forinstance，istwice—and—a—halfaslongandbroadasthehorse—bean，andismuchthinnerandofadifferentshape。
Thevarietiesofthegooseberry，asformerlydescribed，differmuchintheirfruit，buthardlyperceptiblyintheirflowersororgansofvegetation。Withtheplum，thedifferenceslikewiseappeartobegreaterinthefruitthanintheflowersorleaves。Ontheotherhand，theseedofthestrawberry，whichcorrespondswiththefruitoftheplum，differshardlyatall;whilsteveryoneknowshowgreatlythefruit——thatis，theenlargedreceptacle——differsinseveralvarieties。Inapples，pears，andpeachestheflowersandleavesdifferconsiderably，butnot，asfarasIcanjudge，inproportionwiththefruit。
TheChinesedouble—floweringpeaches，ontheotherhand，showthatvarietiesofthistreehavebeenformed，whichdiffermoreinflowerthaninfruit。If，asishighlyprobable，thepeachisthemodifieddescentofthealmond，asurprisingamountofchangehasbeeneffectedinthesamespecies，inthefleshycoveringoftheformerandinthekernelsofthelatter。
Whenpartsstandincloserelationshiptoeachother，suchastheseedandthefleshycoveringofthefruit（whateveritshomologicalnaturemaybe），changesintheoneareusuallyaccompaniedbymodificationsintheother，thoughnotnecessarilytothesamedegree。Withtheplum—tree，forinstance，somevarietiesproduceplumswhicharenearlyalike，butincludestonesextremelydissimilarinshape;whilstconverselyothervarietiesproducedissimilarfruitwithbarelydistinguishablestones;andgenerallythestones，thoughtheyhaveneverbeensubjectedtoselection，differgreatlyintheseveralvarietiesoftheplum。Inothercasesorganswhicharenotmanifestlyrelated，throughsomeunknownbondvarytogether，andareconsequentlyliable，withoutanyintentiononman’spart，tobesimultaneouslyactedonbyselection。Thusthevarietiesofthestock（Matthiola）havebeenselectedsolelyforthebeautyoftheirflowers，buttheseedsdiffergreatlyincolourandsomewhatinsize。Varietiesofthelettucehavebeenselectedsolelyonaccountoftheirleaves，yetproduceseedswhichlikewisedifferincolour。Generally，throughthelawofcorrelation，whenavarietydiffersgreatlyfromitsfellow—varietiesinanyonecharacter，itdifferstoacertainextentinseveralothercharacters。IobservedthisfactwhenIcultivatedtogethermanyvarietiesofthesamespecies，forIusedfirsttomakealistofthevarietieswhichdifferedmostfromeachotherintheirfoliageandmannerofgrowth，afterwardsofthosethatdifferedmostintheirflowers，thenintheirseed—capsules，andlastlyintheirmatureseed;andIfoundthatthesamenamesgenerallyoccurredintwo，three，orfourofthesuccessivelists。
Neverthelessthegreatestamountofdifferencebetweenthevarietieswasalwaysexhibited，asfarasIcouldjudge，bythatpartororganforwhichtheplantwascultivated。
Whenwebearinmindthateachplantwasatfirstcultivatedbecauseusefultoman，andthatitsvariationwasasubsequent，oftenalongsubsequent，event，wecannotexplainthegreateramountofdiversityinthevaluablepartsbysupposingthatspeciesendowedwithanespecialtendencytovaryinanyparticularmannerwereoriginallychosen。Wemustattributetheresulttothevariationsinthesepartshavingbeensuccessivelypreserved，andthuscontinuallyaugmented;whilstothervariations，exceptingsuchasinevitablyappearedthroughcorrelation，wereneglectedandlost。Wemaythereforeinferthatmostplantsmightbemade，throughlong—continuedselection，toyieldracesasdifferentfromoneanotherinanycharacterastheynowareinthosepartsforwhichtheyarevaluedandcultivated。
Withanimalsweseenothingofthesamekind;butasufficientnumberofspecieshavenotbeendomesticatedforafaircomparison。Sheeparevaluedfortheirwool，andthewooldiffersmuchmoreintheseveralracesthanthehairincattle。Neithersheep，goats，Europeancattle，norpigsarevaluedfortheirfleetnessorstrength;andwedonotpossessbreedsdifferingintheserespectsliketheracehorseanddray—horse。Butfleetnessandstrengtharevaluedincamelsanddogs;andwehavewiththeformertheswiftdromedaryandheavycamel;withthelatterthegreyhoundandmastiff。Butdogsarevaluedeveninahigherdegreefortheirmentalqualitiesandsenses;andeveryoneknowshowgreatlytheracesdifferintheserespects。Ontheotherhand，wherethedogiskeptsolelytoserveforfood，asinthePolynesianislandsandChina，itisdescribedasanextremelystupidanimal。（20/89。Godron’Del’Espece’tome2page27。）Blumenbachremarksthat"manydogs，suchasthebadger—dog，haveabuildsomarkedandsoappropriateforparticularpurposes，thatIshouldfinditverydifficulttopersuademyselfthatthisastonishingfigurewasanaccidentalconsequenceofdegeneration。"（20/90。’TheAnthropologicalTreatisesofBlumenbach’1856page292。）HadBlumenbachreflectedonthegreatprincipleofselection，hewouldnothaveusedthetermdegeneration，andhewouldnothavebeenastonishedthatdogsandotheranimalsshouldbecomeexcellentlyadaptedfortheserviceofman。
Onthewholewemayconcludethatwhateverpartorcharacterismostvalued——
whethertheleaves，stems，tubers，bulbs，flowers，fruit，orseedofplants，orthesize，strength，fleetness，hairycovering，orintellectofanimals——
thatcharacterwillalmostinvariablybefoundtopresentthegreatestamountofdifferencebothinkindanddegree。Andthisresultmaybesafelyattributedtomanhavingpreservedduringalongcourseofgenerationsthevariationswhichwereusefultohim，andneglectedtheothers。
Iwillconcludethischapterbysomeremarksonanimportantsubject。Withanimalssuchasthegiraffe，ofwhichthewholestructureisadmirablyco—
ordinatedforcertainpurposes，ithasbeensupposedthatallthepartsmusthavebeensimultaneouslymodified;andithasbeenarguedthat，ontheprincipleofnaturalselection，thisisscarcelypossible。Butinthusarguing，ithasbeentacitlyassumedthatthevariationsmusthave...完整阅读请扫描二维码下载丁香书院APP免费看：