ThecaseofNewZealand，towhichfineislandweasyetowenowidelycultivatedplant，mayseemopposedtothisview;for，whenfirstdiscovered，thenativescultivatedseveralplants;butallinquirersbelieve，inaccordancewiththetraditionsofthenatives，thattheearlyPolynesiancolonistsbroughtwiththemseedsandroots，aswellasthedog，whichhadbeenwiselypreservedduringtheirlongvoyage。ThePolynesiansaresofrequentlylostontheoceanthatthisdegreeofprudencewouldoccurtoanywanderingparty:hencetheearlycolonistsofNewZealand，likethelaterEuropeancolonists，wouldnothavehadanystronginducementtocultivatetheaboriginalplants。AccordingtoDeCandolleweowethirty—
threeusefulplantstoMexico，Peru，andChile;noristhissurprisingwhenwerememberthecivilisedstateoftheinhabitants，asshownbythefactoftheirhavingpractisedartificialirrigationandmadetunnelsthroughhardrockswithouttheuseofironorgunpowder，andwho，asweshallseeinafuturechapter，fullyrecognised，asfarasanimalswereconcerned，andthereforeprobablyinthecaseofplants，theimportantprincipleofselection。WeowesomeplantstoBrazil;andtheearlyvoyagers，namely，VespuciusandCabral，describethecountryasthicklypeopledandcultivated。InNorthAmerica（9/16。ForCanadaseeJ。Cartier’sVoyagein1534;forFloridaseeNarvaezandFerdinanddeSoto’sVoyages。AsIhaveconsultedtheseandotheroldVoyagesinmorethanonegeneralcollectionofVoyages，Idonotgiveprecisereferencestothepages。SeealsoforseveralreferencesAsaGrayinthe’AmericanJournalofScience’volume24
November1857page441。ForthetraditionsofthenativesofNewZealandseeCrawfurd’GrammarandDict。oftheMalayLanguage’1852page260。）thenativescultivatedmaize，pumpkins，gourds，beans，andpeas，"alldifferentfromours，"andtobacco;andwearehardlyjustifiedinassumingthatnoneofourpresentplantsaredescendedfromtheseNorthAmericanforms。HadNorthAmericabeencivilisedforaslongaperiod，andasthicklypeopled，asAsiaorEurope，itisprobablethatthenativevines，walnuts，mulberries，crabs，andplums，wouldhavegivenrise，afteralongcourseofcultivation，toamultitudeofvarieties，someextremelydifferentfromtheirparent—stocks;andescapedseedlingswouldhavecausedintheNew，asintheOldWorld，muchperplexitywithrespecttotheirspecificdistinctnessandparentage。’（9/17。SeeforexampleMr。HewettC。Watson’sremarksonourwildplumsandcherriesandcrabs:’CybeleBritannica’
volume1pages330，334，etc。VanMons（inhis’ArbresFruitiers’1835tome1page444）declaresthathehasfoundthetypesofallourcultivatedvarietiesinwildseedlings，butthenhelooksontheseseedlingsassomanyaboriginalstocks。）
[CEREALIA。
Iwillnowenterondetails。ThecerealscultivatedinEuropeconsistoffourgenera——wheat，rye，barley，andoats。Ofwheatthebestmodernauthorities（9/18。SeeA。DeCandolle’Geograph。Bot。’1855page928etseq。Godron’Del’Espece’1859tome2page70;andMetzger’DieGetreidearten’etc。1841。）makefourorfive，orevensevendistinctspecies;ofrye，one;ofbarley，three;andofoats，two，three，orfourspecies。Sothataltogetherourcerealsarerankedbydifferentauthorsunderfromtentofifteendistinctspecies。Thesehavegivenrisetoamultitudeofvarieties。Itisaremarkablefactthatbotanistsarenotuniversallyagreedontheaboriginalparent—formofanyonecerealplant。
Forinstance，ahighauthoritywritesin1855（9/19。Mr。Benthaminhisreviewentitled’Hist。NotesoncultivatedPlants’byDr。A。Targioni—
Tozzettiin’JournalofHort。Soc。’volume91855page133。Heinformsmethathestillretainsthesameopinion。），"Weourselveshavenohesitationinstatingourconviction，astheresultofallthemostreliableevidence，thatnoneoftheseCerealiaexist，orhaveexisted，trulywildintheirpresentstate，butthatallarecultivatedvarietiesofspeciesnowgrowingingreatabundanceinS。EuropeorW。Asia。"Ontheotherhand，Alph。DeCandolle（9/20。’Geograph。Bot。’page928。Thewholesubjectisdiscussedwithadmirablefulnessandknowledge。）hasadducedabundantevidencethatcommonwheat（Triticumvulgare）hasbeenfoundwildinvariouspartsofAsia，whereitisnotlikelytohaveescapedfromcultivation:andthereissomeforceinM。Godron’sremark，that，supposingtheseplantstobeescapedseedlings（9/21。Godron’Del’Espece’tome2page72。Afewyearsagotheexcellent，thoughmisinterpreted，observationsofM。FabreledmanypersonstobelievethatwheatwasamodifieddescendantofAegilops;butM。
Godron（tome1page165）hasshownbycarefulexperimentsthatthefirststepintheseries，viz。Aegilopstriticoides，isahybridbetweenwheatandAe。ovata。Thefrequencywithwhichthesehybridsspontaneouslyarise，andthegradualmannerinwhichtheAe。triticoidesbecomesconvertedintotruewheat，aloneleaveanydoubtwithrespecttoM。Godron’sconclusions。），astheyhavepropagatedthemselvesinawildstateforseveralgenerations，theircontinuedresemblancetocultivatedwheatrendersitprobablethatthelatterhasretaineditsaboriginalcharacter。
Butthestrongtendencytoinheritance，whichmostofthevarietiesofwheatevince，asweshallpresentlysee，isheregreatlyundervalued。MuchweightmustalsobeattributedtoaremarkbyProfessorHildebrand（9/22。
’DieVerbreitungsmittelderPflanzen’1873page129。）thatwhentheseedsorfruitofcultivatedplantspossessqualitiesdisadvantageoustothemasameansofdistribution，wemayfeelalmostsurethattheynolongerretaintheiraboriginalcondition。Ontheotherhand，M。DeCandolleinsistsstronglyonthefrequentoccurrenceintheAustriandominionsofryeandofonekindofoatsinanapparentlywildcondition。Withtheexceptionofthesetwocases，whichhoweverareratherdoubtful，andwiththeexceptionoftwoformsofwheatandoneofbarley，whichhebelievestohavebeenfoundtrulywild，M。DeCandolledoesnotseemfullysatisfiedwiththeotherreporteddiscoveriesoftheparent—formsofourothercereals。Withrespecttooats，accordingtoMr。Buckmann（9/23。ReporttoBritishAssociationfor1857page207。），thewildEnglishAvenafatuacanbeconvertedbyafewyearsofcarefulcultivationandselectionintoformsalmostidenticalwithtwoverydistinctcultivatedraces。Thewholesubjectoftheoriginandspecificdistinctnessofthevariouscerealplantsisamostdifficultone;butweshallperhapsbeabletojudgealittlebetterafterconsideringtheamountofvariationwhichwheathasundergone。
Metzgerdescribessevenspeciesofwheat，Godronreferstofive，andDeCandolletoonlyfour。Itisnotimprobablethat，besidesthekindsknowninEurope，otherstronglycharacterisedformsexistinthemoredistantpartsoftheworld;forLoiseleur—Deslongchamps（9/24。ConsiderationssurlesCereales’1842—43page29。）speaksofthreenewspeciesorvarieties，senttoEuropein1822fromChineseMongolia，whichheconsidersasbeingthereindigenous。Moorcroft（9/25。’TravelsintheHimalayanProvinces’
etc。1841volume1page224。）alsospeaksofHasorawheatinLadakhasverypeculiar。Ifthosebotanistsarerightwhobelievethatatleastsevenspeciesofwheatoriginallyexisted，thentheamountofvariationinanyimportantcharacterwhichwheathasundergoneundercultivationhasbeenslight;butifonlyfouroralessernumberofspeciesoriginallyexisted，thenitisevidentthatvarietieshavearisensostronglymarked，thattheyhavebeenconsideredbycapablejudgesasspecificallydistinct。Buttheimpossibilityofdecidingwhichformsoughttoberankedasspeciesandwhichasvarieties，makesituselesstospecifyindetailthedifferencesbetweenthevariouskindsofwheat。Speakinggenerally，theorgansofvegetationdifferlittle（9/26。Col。J。LeCouteuronthe’VarietiesofWheat’pages23，79。）;butsomekindsgrowcloseandupright，whilstothersspreadandtrailalongtheground。Thestrawdiffersinbeingmoreorlesshollow，andinquality。Theears（9/27。Loiseleur—Deslongchamps’Consid。
surlesCereales’page11。）differincolourandinshape，beingquadrangular，compressed，ornearlycylindrical;andthefloretsdifferintheirapproximationtoeachother，intheirpubescence，andinbeingmoreorlesselongated。Thepresenceorabsenceofbarbsisaconspicuousdifference，andincertainGramineaeservesevenasagenericcharacter（9/28。SeeanexcellentreviewinHooker’Journ。ofBotany’volume8page82note。）;although，asremarkedbyGodron（9/29。’Del’Espece’tome2page73。）thepresenceofbarbsisvariableincertainwildgrasses，andespeciallyinthosesuchasBromussecalinusandLoliumtemulentum，whichhabituallygrowmingledwithourcerealcrops，andwhichhavethusunintentionallybeenexposedtoculture。Thegrainsdifferinsize，weight，andcolour;inbeingmoreorlessdownyatoneend，inbeingsmoothorwrinkled，inbeingeithernearlyglobular，oval，orelongated;andfinallyininternaltexture，beingtenderorhard，orevenalmosthorny，andintheproportionofglutenwhichtheycontain。
Nearlyalltheracesorspeciesofwheatvary，asGodron（9/30。Ibidtome2
page75。）hasremarked，inanexactlyparallelmanner，——intheseedbeingdownyorglabrous，andincolour，——andinthefloretsbeingbarbedornotbarbed，etc。Thosewhobelievethatallthekindsaredescendedfromasinglewildspeciesmayaccountforthisparallelvariationbytheinheritanceofasimilarconstitution，andaconsequenttendencytovaryinthesamemanner;andthosewhobelieveinthegeneraltheoryofdescentwithmodificationmayextendthisviewtotheseveralspeciesofwheat，ifsucheverexistedinastateofnature。
Althoughfewofthevarietiesofwheatpresentanyconspicuousdifference，theirnumberisgreat。Dalbretcultivatedduringthirtyyearsfrom150to160kinds，andexceptinginthequalityofthegraintheyallkepttrue;
ColonelLeCouteurpossessedupwardsof150，andPhilippar322varieties。
（9/31。ForDalbretandPhilipparseeLoiseleur—Deslongchamps’Consid。surlesCereales’pages45，70。LeCouteuronWheatpages6，14—17。）Aswheatisanannual，wethusseehowstrictlymanytriflingdifferencesincharacterareinheritedthroughmanygenerations。ColonelLeCouteurinsistsstronglyonthissamefact。Inhisperseveringandsuccessfulattemptstoraisenewvarieties，hefoundthattherewasonlyone"securemodetoensurethegrowthofpuresorts，namely，togrowthemfromsinglegrainsorfromsingleears，andtofollowuptheplanbyafterwardssowingonlytheproduceofthemostproductivesoastoformastock。"ButMajorHallett（9/32。SeehisEssayon’PedigreeinWheat’1862;alsopaperreadbeforetheBritishAssociation1869andotherpublications。）hasgonemuchfarther，andbythecontinuedselectionofplantsfromthegrainsofthesameear，duringsuccessivegenerations，hasmadehis’PedigreeinWheat’
（andothercereals）nowfamousinmanyquartersoftheworld。Thegreatamountofvariabilityintheplantsofthesamevarietyisanotherinterestingpoint，whichwouldneverhavebeendetectedexceptbyaneyelongpractisedtothework;thusColonelLeCouteurrelates（9/33。
’VarietiesofWheat’Introductionpage6。Marshallinhis’RuralEconomyofYorkshire’volume2page9remarksthat"ineveryfieldofcornthereisasmuchvarietyasinaherdofcattle。"）thatinafieldofhisownwheat，whichheconsideredatleastaspureasthatofanyofhisneighbours，ProfessorLaGascafoundtwenty—threesorts;andProfessorHenslowhasobservedsimilarfacts。Besidessuchindividualvariations，formssufficientlywellmarkedtobevaluedandtobecomewidelycultivatedsometimessuddenlyappear:thusMr。Shirreffhashadthegoodfortunetoraiseinhislifetimesevennewvarieties，whicharenowextensivelygrowninmanypartsofBritain。（9/34。’Gardener’sChronicle’and’Agricult。
Gazette’1862page963。）
Asinthecaseofmanyotherplants，somevarieties，botholdandnew，arefarmoreconstantincharacterthanothers。ColonelLeCouteurwasforcedtorejectsomeofhisnewsub—varieties，whichhesuspectedhadbeenproducedfromacross，asincorrigiblysportive。OntheotherhandMajorHallett（9/35。’Gardener’sChronicle’November1868page1199。）hasshownhowwonderfullyconstantsomevarietiesare，althoughnotancientones，andalthoughcultivatedinvariouscountries。Withrespecttothetendencytovary，Metzger（9/36。’Getreidearten’1841s。66，91，92，116，117。）givesfromhisownexperiencesomeinterestingfacts:hedescribesthreeSpanishsub—varieties，moreespeciallyoneknowntobeconstantinSpain，whichinGermanyassumedtheirpropercharacteronlyduringhotsummers;anothervarietykepttrueonlyingoodland，butafterhavingbeencultivatedfortwenty—fiveyearsbecamemoreconstant。Hementionstwoothersub—varietieswhichwereatfirstinconstant，butsubsequentlybecame，apparentlywithoutanyselection，accustomedtotheirnewhomes，andretainedtheirpropercharacter。Thesefactsshowwhatsmallchangesintheconditionsoflifecausevariability，andtheyfurthershowthatavarietymaybecomehabituatedtonewconditions。OneisatfirstinclinedtoconcludewithLoiseleur—Deslongchamps，thatwheatcultivatedinthesamecountryisexposedtoremarkablyuniformconditions;butmanuresdiffer，seedistakenfromonesoiltoanother，and，whatisfarmoreimportant，theplantsareexposedaslittleaspossibletostrugglewithotherplants，andarethusenabledtoexistunderdiversifiedconditions。Inastateofnatureeachplantisconfinedtothatparticularstationandkindofnutrimentwhichitcanseizefromtheotherplantsbywhichitissurrounded。
Wheatquicklyassumesnewhabitsoflife。ThesummerandwinterkindswereclassedbyLinnaeusasdistinctspecies;butM。Monnier（9/37。QuotedbyGodron’Del’Espece’volume2page74。Soitis，accordingtoMetzger’Getreidearten’s。18，withsummerandwinterbarley。）hasprovedthatthedifferencebetweenthemisonlytemporary。Hesowedwinter—wheatinspring，andoutofonehundredplantsfouraloneproducedripeseeds;theseweresownandresown，andinthreeyearsplantswererearedwhichripenedalltheirseed。Conversely，nearlyalltheplantsraisedfromsummer—wheat，whichwassowninautumn，perishedfromfrost;butafewweresavedandproducedseed，andinthreeyearsthissummer—varietywasconvertedintoawinter—variety。Henceitisnotsurprisingthatwheatsoonbecomestoacertainextentacclimatised，andthatseedbroughtfromdistantcountriesandsowninEuropevegetatesatfirst，orevenforaconsiderableperiod（9/38。Loiseleur—Deslongchamps’Cereales’part2page224。LeCouteurpage70。Manyotheraccountscouldbeadded。）differentlyfromourEuropeanvarieties。InCanadathefirstsettlers，accordingtoKalm（9/39。’TravelsinNorthAmerica’1753—1761Englishtranslationvolume3page165。），foundtheirwinterstoosevereforwinter—wheatbroughtfromFrance，andtheirsummersoftentooshortforsummer—wheat;andtheythoughtthattheircountrywasuselessforcorncropsuntiltheyprocuredsummer—wheatfromthenorthernpartsofEurope，whichsucceededwell。Itisnotoriousthattheproportionofglutendiffersmuchunderdifferentclimates。Theweightofthegrainisalsoquicklyaffectedbyclimate:Loiseleur—Deslongchamps（9/40。’Cereales’part2pages179—183。）sowednearParis54varieties，obtainedfromtheSouthofFranceandfromtheBlackSea，and52oftheseyieldedseedfrom10to40percentheavierthantheparent—seed。Hethensenttheseh...完整阅读请扫描二维码下载丁香书院APP免费看：