第24章
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  Prof。H。Lecoq,whohasmadeagreatnumberofcrossingsbetweenthedifferentlycolouredvarietiesofMirabilisjalapa(11/122。’Geograph。Bot。

  del’Europe’tome31854page405;and’DelaFecondation’1862page302。)

  findsthatintheseedlingsthecoloursrarelycombine,butformdistinctstripes;orhalftheflowerisofonecolourandhalfofadifferentcolour。Somevarietiesregularlybearflowersstripedwithyellow,white,andred;butplantsofsuchvarietiesoccasionallyproduceonthesamerootbrancheswithuniformlycolouredflowersofallthreetints,andotherbrancheswithhalf—and—halfcolouredflowers,andotherswithmarbledflowers。Gallesio(11/123。’TraiteduCitrus’1811page45。)crossedreciprocallywhiteandredcarnations,andtheseedlingswerestriped;butsomeofthestripedplantsalsoboreentirelywhiteandentirelyredflowers。Someoftheseplantsproducedoneyearredflowersalone,andinthefollowingyearstripedflowers;orconversely,someplants,afterhavingbornefortwoorthreeyearsstripedflowers,wouldrevertandbearexclusivelyredflowers。ItmaybeworthmentioningthatIfertilisedthePURPLESWEET—PEA(Lathyrusodoratus)withpollenfromthelight—colouredPAINTEDLADY:seedlingsraisedfromthesamepodwerenotintermediateincharacter,butperfectlyresembledeitherparent。Laterinthesummer,theplantswhichhadatfirstborneflowersidenticalwiththoseofthePAINTED

  LADY,producedflowersstreakedandblotchedwithpurple;showinginthesedarkermarksatendencytoreversiontothemother—variety。AndrewKnight(11/124。’Transact。Linn。Soc。’volume9page268。)fertilisedtwowhitegrapeswithpollenoftheAleppogrape,whichisdarklyvariegatedbothinitsleavesandfruit。Theresultwasthattheyoungseedlingswerenotatfirstvariegated,butallbecamevariegatedduringthesucceedingsummer;

  besidesthis,manyproducedonthesameplantbunchesofgrapeswhichwereallblack,orallwhite,orlead—colouredstripedwithwhite,orwhitedottedwithminuteblackstripes;andgrapesofalltheseshadescouldfrequentlybefoundonthesamefoot—stalk。

  Iwillappendaverycuriouscase,notofbud—variation,butoftwocoheringembryos,differentincharacterandcontainedwithinthesameseed。Adistinguishedbotanist,Mr。G。H。Thwaites(11/125。’AnnalsandMag。

  ofNat。Hist。’March1848。)statesthataseedfromFuchsiacoccineafertilisedbyF。fulgens,containedtwoembryos,andwas\"atruevegetabletwin。\"Thetwoplantsproducedfromthetwoembryoswere\"extremelydifferentinappearanceandcharacter,\"thoughbothresembledotherhybridsofthesameparentageproducedatthesametime。Thesetwinplants\"werecloselycoherent,belowthetwopairsofcotyledon—leaves,intoasinglecylindricalstem,sothattheyhadsubsequentlytheappearanceofbeingbranchesononetrunk。\"Hadthetwounitedstemsgrownuptotheirfullheight,insteadofdying,acuriouslymixedhybridwouldhavebeenproduced。AmongrelmelondescribedbySageret(11/126。’PomologiePhysiolog。’1830page126。)mayperhapshavethusoriginated;forthetwomainbranches,whicharosefromtwocotyledon—buds,producedverydifferentfruit,——ontheonebranchlikethatofthepaternalvariety,andontheotherbranchliketoacertainextentthatofthematernalvariety,themelonofChina。]

  Inmostofthesecasesofcrossedvarieties,andinsomeofthecasesofcrossedspecies,thecolourspropertobothparentsappearedintheseedlings,assoonastheyfirstflowered,intheformofstripesorlargersegments,oraswholeflowersorfruitofdifferentkindsborneonthesameplant;andinthiscasetheappearanceofthetwocolourscannotstrictlybesaidtobeduetoreversion,buttosomeincapacityoffusion。When,however,thelaterflowersorfruitproducedduringthesameseason,orduringasucceedingyearorgeneration,becomestripedorhalf—and—half,etc。,thesegregationofthetwocoloursisstrictlyacaseofreversionbybud—variation。Whetherallthemanyrecordedcasesofstripedflowersandfruitareduetoprevioushybridisationandreversionisbynomeansclear,forinstancewithpeachesandnectarines,moss—roses,etc。InafuturechapterIshallshowthat,withanimalsofcrossedparentage,thesameindividualhasbeenknowntochangeitscharacterduringgrowth,andtoreverttooneofitsparentswhichitdidnotatfirstresemble。Finally,fromthevariousfactsnowgiven,therecanbenodoubtthatthesameindividualplant,whetherahybridoramongrel,sometimesreturnsinitsleaves,flowers,andfruit,eitherwhollyorbysegments,tobothparent—

  forms。

  ONTHEDIRECTORIMMEDIATEACTIONOFTHEMALEELEMENTONTHEMOTHERFORM。

  Anotherremarkableclassoffactsmustbehereconsidered,firstly,becausetheyhaveahighphysiologicalimportance,andsecondly,becausetheyhavebeensupposedtoaccountforsomecasesofbud—variation。Irefertothedirectactionofthemaleelement,notintheordinarywayontheovules,butoncertainpartsofthefemaleplant,orincaseofanimalsonthesubsequentprogenyofthefemalebyasecondmale。Imaypremisethatwithplantstheovariumandthecoatsoftheovulesareobviouslypartsofthefemale,anditcouldnothavebeenanticipatedthattheywouldhavebeenaffectedbythepollenofaforeignvarietyorspecies,althoughthedevelopmentoftheembryo,insidetheembryonicsack,insidetheovuleandovarium,ofcourse,dependsonthemaleelement。

  [Evenaslongagoas1729itwasobserved(11/127。’PhilosophicalTransact。’volume431744—45page525。)thatwhiteandbluevarietiesofthePea,whenplantedneareachother,mutuallycrossed,nodoubtthroughtheagencyofbees,andintheautumnblueandwhitepeaswerefoundwithinthesamepods。Wiegmannmadeanexactlysimilarobservationinthepresentcentury。Thesameresulthasfollowedseveraltimeswhenavarietywithpeasofonecolourhasbeenartificiallycrossedbyadifferently—colouredvariety。(11/128。Mr。Goss’Transact。Hort。Soc。’volume5page234:andGartner’Bastarderzeugung’1849ss。81and499。)ThesestatementsledGartner,whowashighlyscepticalonthesubject,carefullytotryalongseriesofexperiments:heselectedthemostconstantvarieties,andtheresultconclusivelyshowedthatthecolouroftheskinofthepeaismodifiedwhenpollenofadifferentlycolouredvarietyisused。ThisconclusionhassincebeenconfirmedbyexperimentsmadebytheRev。J。M。

  Berkeley。(11/129。’Gardener’sChronicle’1854page404。)

  Mr。LaxtonofStamford,whilstmakingexperimentsonpeasfortheexpresspurposeofascertainingtheinfluenceofforeignpollenonthemother—

  plant,hasrecently(11/130。Ibid1866page900。)observedanimportantadditionalfact。HefertilisedtheTallSugar—pea,whichbearsverythingreenpods,becomingbrownish—whitewhendry,withpollenofthePurple—

  poddedpea,which,asitsnameexpresses,hasdark—purplepodswithverythickskin,becomingpalereddishpurplewhendry。Mr。Laxtonhascultivatedthetallsugar—peaduringtwentyyears,andhasneverseenorheardofitproducingapurplepod:nevertheless,aflowerfertilisedbypollenfromthepurple—podyieldedapodcloudedwithpurplish—redwhichMr。Laxtonkindlygavetome。Aspaceofabouttwoinchesinlengthtowardstheextremityofthepod,andasmallerspacenearthestalk,werethuscoloured。Oncomparingthecolourwiththatofthepurplepod,bothpodshavingbeenfirstdriedandthensoakedinwater,itwasfoundtobeidenticallythesame;andinboththecolourwasconfinedtothecellslyingimmediatelybeneaththeouterskinofthepod。Thevalvesofthecrossedpodwerealsodecidedlythickerandstrongerthanthoseofthepodsofthemother—plant,butthismaypossiblyhavebeenanaccidentalcircumstance,forIknownothowfartheirthicknessisavariablecharacterintheTallSugar—pea。

  ThepeasoftheTallSugar—pea,whendry,arepalegreenish—brown,thicklycoveredwithdotsofdarkpurplesominuteastobevisibleonlythroughalens,andMr。Laxtonhasneverseenorheardofthisvarietyproducingapurplepea;butinthecrossedpodoneofthepeaswasofauniformbeautifulviolet—purpletint,andasecondwasirregularlycloudedwithpalepurple。Thecolourliesintheouterofthetwocoatswhichsurroundthepea。Asthepeasofthepurple—poddedvarietywhendryareofapalegreenish—buff,itwouldatfirstappearthatthisremarkablechangeofcolourinthepeasinthecrossedpodcouldnothavebeencausedbythedirectactionofthepollenofthepurple—pod:butwhenwebearinmindthatthislattervarietyhaspurpleflowers,purplemarksonitsstipules,andpurplepods;andthattheTallSugar—pealikewisehaspurpleflowersandstipules,andmicroscopicallyminutepurpledotsonthepeas,wecanhardlydoubtthatthetendencytotheproductionofpurpleinbothparentshasincombinationmodifiedthecolourofthepeasinthecrossedpod。

  Afterhavingexaminedthesespecimens,Icrossedthesametwovarieties,andthepeasinonepodbutnotthepodsthemselves,werecloudedandtintedwithpurplish—redinamuchmoreconspicuousmannerthanthepeasintheuncrossedpodsproducedatthesametimebythesameplants。ImaynoticeasacautionthatMr。Laxtonsentmevariousothercrossedpeasslightly,orevengreatly,modifiedincolour;butthechangeinthesecaseswasdue,ashadbeensuspectedbyMr。Laxton,tothealteredcolourofthecotyledons,seenthroughthetransparentcoatsofthepeas;andasthecotyledonsarepartsoftheembryo,thesecasesarenotinanywayremarkable。

  TurningnowtothegenusMatthiola。Thepollenofonekindofstocksometimesaffectsthecolouroftheseedsofanotherkind,usedasthemother—plant。Igivethefollowingcasethemorereadily,asGartnerdoubtedsimilarstatementspreviouslymadewithrespecttothestockbyotherobservers。Awell—knownhorticulturist,MajorTrevorClarke,informsme(11/131。SeealsoapaperbythisobserverreadbeforetheInternationalHort。andBot。CongressofLondon1866。)thattheseedsofthelargered—

  floweredBIENNIALstock,Matthiolaannua(CocardeauoftheFrench),arelightbrown,andthoseofthepurplebranchingQueenstock(M。incana)areviolet—black;andhefoundthat,whenflowersoftheredstockwerefertilisedbypollenfromthepurplestock,theyyieldedaboutfiftypercentofBLACKseeds。Hesentmefourpodsfromaredfloweredplant,twoofwhichhadbeenfertilisedbytheirownpollen,andtheyincludedpalebrownseed;andtwowhichhadbeencrossedbypollenfromthepurplekind,andtheyincludedseedsalldeeplytingedwithblack。Theselatterseedsyieldedpurple—floweredplantsliketheirfather;whilstthepalebrownseedsyieldednormalred—floweredplants;andMajorClarke,bysowingsimilarseeds,hasobservedonagreaterscalethesameresult。Theevidenceinthiscaseofthedirectactionofthepollenofonespeciesonthecolouroftheseedsofanotherspeciesappearstomeconclusive。

  Gallesio(11/132。’TraiteduCitrus’page40。)fertilisedtheflowersofanorangewithpollenfromthelemon;andonefruitthusproducedborealongitudinalstripeofpeelhavingthecolour,flavour,andothercharactersofthelemon。Mr。Anderson(11/133。’Transact。Hort。Soc。’

  volume3page318。Seealsovolume5page65。)fertilisedagreen—fleshedmelonwithpollenfromascarlet—fleshedkind;intwoofthefruits\"asensiblechangewasperceptible:andfourotherfruitsweresomewhatalteredbothinternallyandexternally。\"Theseedsofthetwofirst—

  mentionedfruitsproducedplantspartakingofthegoodpropertiesofbothparents。IntheUnitedStates,whereCucurbitaceaearelargelycultivated,itisthepopularbelief(11/134。Prof。AsaGray’Proc。Acad。Sc。’Bostonvolume41860page21。IhavereceivedstatementstothesameeffectfromotherpersonsintheUnitedStates。)thatthefruitisthusdirectlyaffectedhyforeignpollen;andIhavereceivedasimilarstatementwithrespecttothecucumberinEngland。Itisbelievedthatgrapeshavebeenthusaffectedincolour,size,andshape:inFranceapale—colouredgrapehaditsjuicetintedbythepollenofthedark—colouredTeinturier;inGermanyavarietyboreberrieswhichwereaffectedbythepollenoftwoadjoiningkinds;someoftheberriesbeingonlypartiallyaffectedormottled。(11/135。FortheFrenchcasesee’Journ。Hort。Soc。’volume1newseries1866page50。ForGermanyseeM。JackquotedinHenfrey’s’BotanicalGazette’volume1page277。AcaseinEnglandhasrecentlybeenalludedtobytheRev。J。M。BerkeleybeforetheHort。Soc。ofLondon。)

  Aslongagoas1751(11/136。’PhilosophicalTransactions’volume471751—52

  page206。)itwasobservedthat,whendifferently—colouredvarietiesofmaizegrewneareachother,theymutuallyaffectedeachother’sseeds,andthisisnowapopularbeliefintheUnitedStates。Dr。Savi(11/137。

  Gallesio’TeoriadellaRiproduzione’1816page95。)triedtheexperimentwithcare:hesowedyellowandblack—seededmaizetogether,andonthesameearsomeoftheseedswereyellow,someblack,andsomemottled,thedifferentlycolouredseedsbeingarrangedirregularlyorinrows。Prof。

  Hildebrandhasrepeatedtheexperiment(11/138。’Bot。Zeitung’May1868

  page326。)withtheprecautionofascertainingthatthemother—plantwastrue。Akindbearingyellowgrainswasfertilisedwithpollenofakindhavingbrowngrains,andtwoearsproducedyellowgrainsmingledwithothersofadirtyviolettint。Athirdearhadonlyyellowgrains,butonesideofthespindlewastintedofareddish—brown;sothatherewehavetheimportantfactoftheinfluenceoftheforeignpollenextendingtotheaxis。Mr。Arnold,inCanada,variedtheexperimentinaninterestingmanner:\"afemaleflowerwassubjectedfirsttotheactionofpollenfromayellowvariety,andthentothatfromawhitevariety;theresultwasanear,eachgrainofwhichwasyellowbelowandwhiteabove。\"(11/139。SeeDr。J。Stockton—Hough’AmericanNaturalist’January1874page29。)Withotherplantsithasoccasionallybeenobservedthatthecrossedoffspringshowedtheinfluenceoftwokindsofpollen,butinthiscasethetwokindsaffectedthemother—plant。

  Mr。Sabinestates(11/140。’Transact。Hort。Soc。’volume5page69。)thathehasseentheformofthenearlyglobularseed—capsuleofAmaryllisvittataalteredbytheapplicationofthepollenofanotherspecies,ofwhichthecapsulehasgibbousangles。Withanalliedgenus,awell—knownbotanist,Maximowicz,hasdescribedindetailthestrikingresultsofreciprocallyfertilisingLiliumbulbiferumanddavuricumwitheachother’spollen。Eachspeciesproducedfruitnotlikeitsown,butalmostidenticalwiththatofthepollen—bearingspecies;butfromanaccidentonlythefruitofthelatterspecieswascarefullyexamined;theseedswereintermediateinthedevelopmentoftheirwings。(11/141。’Bull。del’Acad。

  Imp。deSt。Petersburg’tome17page275,1872。TheauthorgivesreferencestothosecasesintheSo1anaceaeoffruitaffectedbyforeignpollen,butasitdoesnotappearthatthemother—plantwasartificiallyfertilised,I

  havenotenteredintodetails。)

  FritzMullerfertilisedCattleyaleopoldiwithpollenofEpidendroncinnabarinum;andthecapsulescontainedveryfewseeds;butthesepresentedamostwonderfulappearance,which,fromthedescriptiongiven,twobotanists,HildebrandandMaximowicz,attributetothedirectactionofthepollenoftheEpidendron。(11/142。’Bot。Zeitung’September1868page631。ForMaximowicz’sjudgmentseethepaperlastreferredto。)

  Mr。J。AndersonHenry(11/143。’JournalofHorticulture’January20,1863

  page46。)crossedRhododendrondalhousiaewiththepollenofR。nuttallii,whichisoneofthelargest—floweredandnoblestspeciesofthegenus。Thelargestpodproducedbytheformerspecies,whenfertilisedwithitsownpollen,measured12/8inchinlengthand11/2ingirth;whilstthreeofthepodswhichhadbeenfertilisedbypollenofR。nuttalliimeasured15/8

  inchinlengthandnolessthan2inchesingirth。Heretheeffectoftheforeignpollenwasapparentlyconfinedtoincreasingthesizeoftheovarium;butwemustbecautiousinassuming,asthefollowingcaseshows,thatsizehadbeentransferredfromthemaleparenttothecapsuleofthefemaleplant。Mr。HenryfertilisedArabisblepharophyllawithpollenofA。

  soyeri,andthepodsthusproduced,ofwhichhewassokindastosendmedetailedmeasurementsandsketches,weremuchlargerinalltheirdimensionsthanthosenaturallyproducedbyeitherthemaleorfemaleparent—species。Inafuturechapterweshallseethattheorgansofvegetationinhybridplants,independentlyofthecharacterofeitherparent,aresometimesdevelopedtoamonstroussize;andtheincreasedsizeofthepodsintheforegoingcasesmaybeananalogousfact。Ontheotherhand,M。deSaportainformsmethatanisolatedfemaleplantofPistaciaveraisveryapttobefertilisedbythepollenofneighbouringplantsofP。terebinthus,andinthiscasethefruitsareonlyhalftheirpropersize,whichheattributestotheinfluenceofthepollenofP。terebinthus。

  Nocaseofthedirectactionofthepollenofonevarietyonanotherisbetterauthenticatedormoreremarkablethanthatofthecommonapple。Thefruithereconsistsofthelowerpartofthecalyxandoftheupperpartoftheflower—peduncle(11/144。SeeonthisheadthehighauthorityofProf。

  Decaisneinapapertranslatedin’Journ。Hort。Soc。’volume1newseries1866page48。)inametamorphosedcondition,sothattheeffectoftheforeignpollenhasextendedevenbeyondthelimitsoftheovarium。CasesofapplesthusaffectedwererecordedbyBradleyintheearlypartofthelastcentury;andothercasesaregiveninoldvolumesofthe’PhilosophicalTransactions’(11/145。Volume431744—45page525volume451747—48page602。);inoneoftheseaRussetingappleandanadjoiningkindmutuallyaffectedeachother’sfruit;andinanothercaseasmoothappleaffectedarough—coatedkind。Anotherinstancehasbeengiven(11/146。’Transact。

  Hort。Soc。’volume5pages65and68。SeealsoProf。Hildebrandwithacolouredfigurein’Bot。Zeitung’May15,1868page327。Puvisalsohascollected’DeLaDegeneration’1837page36)severalotherinstances;butitisnotinallcasespossibletodistinguishbetweenthedirectactionofforeignpollenandbud—variations。)oftwoverydifferentapple—treesgrowingclosetoeachother,whichborefruitresemblingeachother,butonlyontheadjoiningbranches。Itis,however,almostsuperfluoustoadducetheseorothercases,afterthatoftheSt。Valeryapple,theflowerswhich,fromtheabortionofthestamens,donotproducepollen,butarefertilisedbythegirlsoftheneighbourhoodwithpollenofmanykinds;

  andtheybearfruit,\"differingfromoneanotherinsize,flavour,andcolour,butresemblingincharacterthehermaphroditekindsbywhichtheyhavebeenfertilised。\"(11/147。T。deClermont—Tonnerrein’Mem。delaSoc。

  Linn。deParis’tome31825page164。)]

  Ihavenowshown,ontheauthorityofseveralexcellentobservers,inthecaseofplantsbelongingtowidelydifferentorders,thatthepollenofonespeciesorvariety,whenappliedtothefemaleofadistinctform,occasionallycausesthecoatsoftheseeds,theovariumorfruit,includingeventhecalyxandupperpartofthepeduncleoftheapple,andtheaxisoftheearinmaize,tobemodified。Sometimesthewholeovariumoralltheseedsarethusaffected;sometimesonlyacertainnumberoftheseeds,asinthecaseofthepea,oronlyapartoftheovarium,aswiththestripedorange,mottledgrapes,andmaize,isthusaffected。Itmustnotbesupposedthatanydirectorimmediateeffectinvariablyfollowstheuseofforeignpollen:thisisfarfrombeingthecase;norisitknownonwhatconditionstheresultdepends。Mr。Knight(11/148。’Transact。ofHort。

  Soc。’volume5page68。)expresslystatesthathehasneverseenthefruitthusaffected,thoughhecrossedthousandsofappleandotherfruit—trees。

  Thereisnottheleastreasontobelievethatabranchwhichhasborneseedorfruitdirectlymodifiedbyforeignpollenisitselfaffected,soasafterwardstoproducemodifiedbuds;suchanoccurrence,fromthetemporaryconnectionoftheflowerwiththestem,wouldbehardlypossible。Hence,butveryfew,ifany,ofthecasesofbud—variationinthefruitoftrees,givenintheearlypartofthischaptercanbeaccountedforbytheactionofforeignpollen;forsuchfruitshavecommonlybeenpropagatedbybuddingorgrafting。Itisalsoobviousthatchangesofcolourinflowers,whichnecessarilysupervenelongbeforetheyarereadyforfertilisation,andchangesintheshapeorcolourofleaves,whenduetotheappearanceofmodifiedbuds,canhavenorelationtotheactionofforeignpollen。

  Theproofsoftheactionofforeignpollenonthemother—planthavebeengiveninconsiderabledetail,becausethisaction,asweshallseeinafuturechapter,isofthehighesttheoreticalimportance,andbecauseitisinitselfaremarkableandapparentlyanomalouscircumstance。Thatitisremarkableunderaphysiologicalpointofviewisclear,forthemaleelementnotonlyaffects,inaccordancewithitsproperfunction,thegerm,butatthesametimevariouspartsofthemother—plant,inthesamemanner,asitaffectsthesamepartintheseminaloffspringfromthesametwoparents。Wethuslearnthatanovuleisnotindispensableforthereceptionoftheinfluenceofthemaleelement。Butthisdirectactionofthemaleelementisnotsoanomalousasitatfirstappears,foritcomesintoplayintheordinaryfertilisationofmanyflowers。GartnergraduallyincreasedthenumberofpollengrainsuntilhesucceededinfertilisingaMalva,andhas(11/149。BeitragezurKenntnissderBefruchtung’1844s。347—351。)

  provedthatmanygrainsarefirstexpendedinthedevelopment,or,asheexpressesit,inthesatiation,ofthepistilandovarium。Again,whenoneplantisfertilisedbyawidelydistinctspecies,itoftenhappensthattheovariumisfullyandquicklydevelopedwithoutanyseedsbeingformed;orthecoatsoftheseedsareformedwithoutanyembryobeingdevelopedwithin。Prof。Hildebrand,also,haslatelyshown(11/150。’DieFruchtbildungderOrchideen,einBeweisfurdiedoppelteWirkungdesPollens’’BotanischeZeitung’No。44etseq。October30,1865;andAugust4,1865s。249。)that,inthenormalfertilisationofseveralOrchideae,theactionoftheplant’sownpollenisnecessaryforthedevelopmentoftheovarium;andthatthisdevelopmenttakesplacenotonlylongbeforethepollen—tubeshavereachedtheovules,butevenbeforetheplacentaeandovuleshavebeenformed;sothatwiththeseorchidsthepollenactsdirectlyontheovarium。Ontheotherhand,wemustnotoverratetheefficacyofpolleninthecaseofhybridisedplants,foranembryomaybeformedanditsinfluenceexcitethesurroundingtissuesofthemother—

  plant,andthenperishataveryearlyageandbethusoverlooked。Again,itiswellknownthatwithmanyplantstheovariummaybefullydeveloped,thoughpollenbewhollyexcluded。Lastly,Mr。Smith,thelateCuratoratKew(asIhearthroughDr。Hooker),observedwithanorchid,theBonateaspeciosa,thesingularfactthatthedevelopmentoftheovariumcouldbeeffectedbythemechanicalirritationofthestigma。Nevertheless,fromthenumberofthepollen—grainsexpended\"inthesatiationoftheovariumandpistil,\"——fromthegeneralityoftheformationoftheovariumandseed—

  coatsinhybridisedplantswhichproducenoseeds,——andfromDr。

  Hildebrand’sobservationsonorchids,wemayadmitthatinmostcasestheswellingoftheovarium,andtheformationoftheseed—coatsareatleastaided,ifnotwhollycaused,bythedirectactionofthepollen,independentlyoftheinterventionofthefertilisedgerm。Therefore,inthepreviouslygivencaseswehaveonlytobelieveinthefurtherpowerofpollen,whenappliedtoadistinctspeciesorvariety,toinfluencetheshape,size,colour,texture,etc。,ofcertainpartsofthemother—plant。

  Turningnowtotheanimalkingdom。Ifwecouldimaginethesameflowertoyieldseedsduringsuccessiveyears,thenitwouldnotbeverysurprisingthataflowerofwhichtheovariumhadbeenmodifiedbyforeignpollenshouldnextyearproduce,whenself—fertilised,offspringmodifiedbythepreviousmaleinfluence。Closelyanalogouscaseshaveactuallyoccurredwithanimals。InthecaseoftenquotedfromLordMorton(11/151。’Philos。

  Transact。’1821page20。)anearlypurely—bredArabianchestnutmareboreahybridtoaquagga;shewassubsequentlysenttoSirGoreOuseley,andproducedtwocoltsbyablackArabianhorse。Thesecoltswerepartiallydun—coloured,andwerestripedonthelegsmoreplainlythantherealhybrid,oreventhanthequagga。Oneofthetwocoltshaditsneckandsomeotherpartsofitsbodyplainlymarkedwithstripes。Stripesonthebody,nottomentionthoseonthelegs,areextremelyrare,——Ispeakafterhavinglongattendedtothesubject,——withhorsesofallkindsinEurope,andarealmostunknowninthecaseofArabians。Butwhatmakesthecasestillmorestrikingisthatinthesecoltsthehairofthemaneresembledthatofthequagga,beingshort,stiff,andupright。HencetherecanbenodoubtthatthequaggaaffectedthecharacteroftheoffspringsubsequentlybegotbytheblackArabianhorse。Mr。JennerWeirinformsmeofastrictlyparallelcase:hisneighbourMr。Lethbridge,ofBlackheath,hasahorse,bredbyLordMostyn,whichhadpreviouslyborneafoalbyaquagga。Thishorseisdunwithadarkstripedowntheback,faintstripesontheforeheadbetweentheeyes,plainstripesontheinnersideofthefore—legsandrathermorefaintonesonthehind—legs,withnoshoulder—stripe。Themanegrowsmuchlowerontheforeheadthaninthehorse,butnotsolowasinthequaggaorzebra。Thehoofsareproportionallylongerthaninthehorse,——somuchsothatthefarrierwhofirstshodthisanimal,andknewnothingofitsorigin,said,\"HadInotseenIwasshoeingahorse,IshouldhavethoughtIwasshoeingadonkey。\"

  Withrespecttothevarietiesofourdomesticatedanimals,manysimilarandwell—authenticatedfactshavebeenpublished(11/152。Dr。Alex。Harveyon’AremarkableEffectofCross—breeding’1851。Onthe’PhysiologyofBreeding’byMr。ReginaldOrton1855。’Intermarriage’byAlex。Walker1837。

  ’L’HerediteNaturelle’byDr。ProsperLucastome2page58。Mr。W。Sedgwickin’BritishandForeignMedico—ChirurgicalReview’1863Julypage183。

  Bronninhis’GeschichtederNatur’1843b。2s。127hascollectedseveralcaseswithrespecttomares,sows,anddogs。Mr。W。C。L。Martin(’HistoryoftheDog’1845page104)sayshecanpersonallyvouchfortheinfluenceofthemaleparentonsubsequentlittersbyotherdogs。AFrenchpoet,JacquesSavary,whowrotein1665ondogs,wasawareofthissingularfact。Dr。

  Bowerbankhasgivenusthefollowingstrikingcase:——Ablack,hairlessBarbarybitchwasfirstaccidentallyimpregnatedbyamongrelspanielwithlongbrownhair,andsheproducedfivepuppies,threeofwhichwerehairlessandtwocoveredwithSHORTbrownhair。Thenexttimeshewasputtoablack,hairlessBarbarydog;\"butthemischiefhadbeenimplantedinthemother,andagainabouthalfthelitterlookedlikepureBarbarys,andtheotherhalfliketheSHORT—hairedprogenyofthefirstfather。\"Ihavegiveninthetextonecasewithpigs;anequallystrikingonehasbeenrecentlypublishedinGermany,’Illust。Landwirth。Zeitung’1868November17page143。ItisworthnoticethatfarmersinS。Brazil(asIhearfromFritzMuller),andattheC。ofGoodHope(asIhaveheardfromtwotrustworthypersons)areconvincedthatmareswhichhaveoncebornemules,whensubsequentlyputtohorses,areextremelyliabletoproducecolts,stripedlikeamule。Dr。WilckensofPogarthgives(’JahrbuchLandwirthschaft’21869page325)astrikingandanalogouscase。Amerinoram,havingtwosmalllappetsorflapsofskinontheneck,wasinthewinterof1861—62puttoseveralMerinoewes,allofwhomborelambswithsimilarflapsontheirnecks。Theramwaskilledinthespringof1862andsubsequentlytohisdeaththeeweswereputtootherMerinorams,andin1863toSouthdownrams,noneofwhomeverhavenecklappets:nevertheless,evenaslongafterwardsas1867,severaloftheseewesproducedlambsbearingtheseappendages。),andothershavebeencommunicatedtome,plainlyshowingtheinfluenceofthefirstmaleontheprogenysubsequentlybornebythemothertoothermales。Itwillsufficetogiveasingleinstance,recordedinthe’PhilosophicalTransactions,’inapaperfollowingthatbyLordMorton:Mr。GilesputasowofLordWestern’sblackandwhiteEssexbreedtoawildboarofadeepchestnutcolour;andthe\"pigsproducedpartookinappearanceofbothboarandsow,butinsomethechestnutcolouroftheboarstronglyprevailed。\"Aftertheboarhadlongbeendead,thesowwasputtoaboarofherownblackandwhitebreed——akindwhichiswellknowntobreedverytrueandnevertoshowanychestnutcolour,——yetfromthisunionthesowproducedsomeyoungpigswhichwereplainlymarkedwiththesamechestnuttintasinthefirstlitter。Similarcaseshavesofrequentlyoccurred,thatcarefulbreedersavoidputtingachoicefemaleofanyanimaltoaninferiormale,onaccountoftheinjurytohersubsequentprogenywhichmaybeexpectedtofollow。

  Somephysiologistshaveattemptedtoaccountfortheseremarkableresultsfromapreviousimpregnation,bytheimaginationofthemotherhavingbeenstronglyaffected;butitwillhereafterbeseenthatthereareveryslightgroundsforanysuchbelief。Otherphysiologistsattributetheresulttothecloseattachmentandfreelyintercommunicatingblood—vesselsbetweenthemodifiedembryoandmother。Buttheanalogyfromtheactionofforeignpollenontheovarium,seed—coats,andotherpartsofthemother—plant,stronglysupportsthebeliefthatwithanimalsthemaleelementactsdirectlyonthefemale,andnotthroughthecrossedembryo。Withbirdsthereisnocloseconnectionbetweentheembryoandmother;yetacarefulobserver,Dr。Chapuis,states(11/153。’LePigeonVoyageurBelge’1865page59。)thatwithpigeonstheinfluenceofafirstmalesometimesmakesitselfperceivedinthesucceedingbroods;butthisstatementrequiresconfirmation。

  CONCLUSIONANDSUMMARYOFTHECHAPTER。

  Thefactsgiveninthelatterhalfofthischapterarewellworthyofconsideration,astheyshowusinhowmanyextraordinarymodestheunionofoneformwithanothermayleadtothemodificationoftheseminaloffspringorofthebuds,afterwardsproduced。

  Thereisnothingsurprisingintheoffspringofspeciesorvarietiescrossedintheordinarymannerbeingmodified;butthecaseoftwoplantswithinthesameseed,whichcohereanddifferfromeachother,iscurious。

  Whenabudisformedafterthecellulartissueoftwospeciesortwovarietieshavebeenunited,anditpartakesofthecharactersofbothparents,thecaseiswonderful。ButIneednothererepeatwhathasbeensolatelysaidonthissubject。Wehavealsoseenthatinthecaseofplantsthemaleelementmayaffectinadirectmannerthetissuesofthemother,andwithanimalsmayleadtothemodificationofherfutureprogeny。Inthevegetablekingdomtheoffspringfromacrossbetweentwospeciesorvarieties,whethereffectedbyseminalgenerationorbygrafting,oftenrevert,toagreaterorlessdegree,inthefirstorinasucceedinggeneration,tothetwoparent—forms;andthisreversionmayaffectthewholeflower,fruit,orleaf—bud,oronlythehalforasmallersegmentofasingleorgan。Insomecases,however,suchsegregationofcharacterapparentlydependsonanincapacityforunionratherthanonreversion,fortheflowersorfruitwhicharefirstproduceddisplaybysegmentsthecharactersofbothparents。Thevariousfactsheregivenoughttobewellconsideredbyanyonewhowishestoembraceunderasinglepointofviewthemanymodesofreproductionbygemmation,division,andsexualunion,thereparationoflostparts,variation,inheritance,reversion,andothersuchphenomena。TowardsthecloseofthesecondvolumeIshallattempttoconnectthesefactstogetherbythehypothesisofpangenesis。

  IntheearlyhalfofthepresentchapterIhavegivenalonglistofplantsinwhichthroughbud—variation,thatis,independentlyofreproductionbyseed,thefruithassuddenlybecomemodifiedinsize,colour,flavour,hairiness,shape,andtimeofmaturity;flowershavesimilarlychangedinshape,colour,inbeingdouble,andgreatlyinthecharacterofthecalyx;

  youngbranchesorshootshavechangedincolour,inbearingspinesandinhabitofgrowth,asinclimbingorinweeping;leaveshavechangedinbecomingvariegated,inshape,periodofunfolding,andintheirarrangementontheaxis。Budsofallkinds,whetherproducedonordinarybranchesoronsubterraneanstems,whethersimpleormuchmodifiedandsuppliedwithastockofnutriment,asintubersandbulbs,areallliabletosuddenvariationsofthesamegeneralnature。

  Inthelist,manyofthecasesarecertainlyduetoreversiontocharactersnotacquiredfromacross,butwhichwereformerlypresentandhavesincebeenlostforalongerorshortertime;——aswhenabudonavariegatedplantproducesplainleaves,orwhenthevariously—colouredflowersoftheChrysanthemumreverttotheaboriginalyellowtint。Manyothercasesincludedinthelistareprobablyduetotheplantsbeingofcrossedparentage,andtothebudsrevertingeithercompletelyorbysegmentstooneofthetwoparent—forms。(11/154。Itmaybeworthwhiletocallattentiontotheseveralmeansbywhichflowersandfruitbecomestripedormottled。Firstly,bythedirectactionofthepollenofanothervarietyorspecies,asinthecasesgivenoforangesandmaize。Secondly,incrossesofthefirstgeneration,whenthecoloursofthetwoparentsdonotreadilyunite,aswithMirabilisandDianthus。Thirdly,incrossedplantsofasubsequentgenerationbyreversion,througheitherbudorseminalgeneration。Fourthly,byreversiontoacharacternotoriginallygainedbyacross,butwhichhadlongbeenlost,aswithwhite—floweredvarieties,whichweshallhereafterseeoftenbecomestripedwithsomeothercolour。

  Lastly,therearecases,aswhenpeachesareproducedwithahalforquarterofthefruitlikeanectarine,inwhichthechangeisapparentlyduetomerevariation,througheitherbudorseminalgeneration。)

  WemaysuspectthatthestrongtendencyintheChrysanthemumtoproducebybud—variationdifferently—colouredflowers,resultsfromthevarietieshavingbeenatsometimeintentionallyoraccidentallycrossed;andthisiscertainlythecasewithsomekindsofPelargonium。Soitmaybetoalargeextentwiththebud—varietiesoftheDahlia,andwiththe\"brokencolours\"ofTulips。When,however,aplantrevertsbybud—variationtoitstwoparentforms,ortooneofthem,itsometimesdoesnotrevertperfectly,butassumesasomewhatnewcharacter,——ofwhichfact,instanceshavebeengiven,andCarrieregives(11/155。’ProductiondesVarietes’page37。)

  anotherinthecherry。

  Manycasesofbud—variation,however,cannotbeattributedtoreversion,buttoso—calledspontaneousvariability,asissocommonwithcultivatedplantsraisedfromseed。AsasinglevarietyoftheChrysanthemumhasproducedbybudssixothervarieties,andasonevarietyofthegooseberryhasborneatthesametimefourdistinctkindsoffruit,itisscarcelypossibletobelievethatallthesevariationsareduetoreversion。Wecanhardlybelieve,asremarkedinapreviouschapter,thatallthemanypeacheswhichhaveyieldednectarine—budsareofcrossedparentage。Lastly,insuchcasesasthatofthemoss—rose,withitspeculiarcalyx,andoftherosewhichbearsoppositeleaves,inthatoftheImatophyllum,etc。,thereisnoknownnaturalspeciesorvarietyfromwhichthecharactersinquestioncouldhavebeenderivedbyacross。Wemustattributeallsuchcasestotheappearanceofabsolutelynewcharactersinthebuds。Thevarietieswhichhavethusarisencannotbedistinguishedbyanyexternalcharacterfromseedlings;thisisnotoriouslythecasewiththevarietiesoftheRose,Azalea,andmanyotherplants。Itdeservesnoticethatalltheplantswhichhaveyieldedbud—variationshavelikewisevariedgreatlybyseed。

  Theplantswhichhavevariedbybudsbelongtosomanyordersthatwemayinferthatalmosteveryplantwouldbeliabletovariation,ifplacedundertheproperexcitingconditions。Theseconditions,asfaraswecanjudge,mainlydependonlong—continuedandhighcultivation;foralmostalltheplantsintheforegoinglistareperennials,andhavebeenlargelypropagatedinmanysoils,underdifferentclimates,bycuttings,offsets,bulbs,tubers,andespeciallybybuddingorgrafting。Theinstancesofannualsvaryingbybuds,orproducingonthesameplantdifferentlycolouredflowers,arecomparativelyrare:Hopkirk(11/156。’FloraAnomala’

  page164。)hasseenthiswithConvolvulustricolor;anditisnotuncommonwiththeBalsamandannualDelphinium。AccordingtoSirR。Schomburgk,plantsfromthewarmertemperateregions,whencultivatedunderthehotclimateofSt。Domingo,areeminentlyliabletobud—variation。IaminformedbyMr。Sedgwickthatmoss—roseswhichhaveoftenbeentakentoCalcuttaalwaystherelosetheirmossiness;butchangeofclimateisbynomeansanecessarycontingent,asweseewiththegooseberry,currant,andinmanyothercases。Plantslivingundertheirnaturalconditionsareveryrarelysubjecttobud—variation。Variegatedleaveshave,however,beenobservedundersuchcircumstances;andIhavegivenaninstanceofvariationbybudsonanash—treeplantedinornamentalgrounds,butitisdoubtfulwhethersuchatreecanbeconsideredaslivingunderstrictlynaturalconditions。Gartnerhasseenwhiteanddark—redflowersproducedfromthesamerootofthewildAchilleamillefolium;andProf。CasparyhasseenacompletelywildViolaluteabearingflowersoftwodifferentcoloursandsizes。(11/157。’Schriftenderphysisch—okon。Gesell。zuKonigsberg’b。

  6February3,1865s。4。)

  Aswildplantsaresorarelyliabletobud—variation,whilsthighlycultivatedplantslongpropagatedbyartificialmeanshaveyieldedmanyvarietiesbythisformofreproduction,weareledthroughaseriessuchasthefollowing,——namely,alltheeyesinthesametuberofthepotatovaryinginthesamemanner,——allthefruitonapurpleplum—treesuddenlybecomingyellow,——allthefruitonadouble—floweredalmondsuddenlybecomingpeachlike,——allthebudsongraftedtreesbeinginaveryslightdegreeaffectedbythestockonwhichtheyhavebeenworked,——alltheflowersonatransplantedheartseasechangingforatimeincolour,size,andshape,——weareledbysuchaseriestolookateverycaseofbud—

  variationasthedirectresultoftheconditionsoflifetowhichtheplanthasbeenexposed。Ontheotherhand,plantsofthesamevarietymaybecultivatedintwoadjoiningbeds,apparentlyunderexactlythesameconditions,andthoseintheonebed,asCarriereinsists(11/158。

  ’ProductiondesVarietes’pages58,70。)willproducemanybud—variations,andthoseintheothernotasingleone。Again,ifwelooktosuchcasesasthatofapeach—treewhich,afterhavingbeencultivatedbytensofthousandsduringmanyyearsinmanycountries,andafterhavingannuallyproducedmillionsofbuds,allofwhichhaveapparentlybeenexposedtopreciselythesameconditions,yetatlastsuddenlyproducesasinglebudwithitswholecharactergreatlytransformed,wearedriventotheconclusionthatthetransformationstandsinnoDIRECTrelationtotheconditionsoflife。

  Wehaveseenthatvarietiesproducedfromseedsandfrombudsresembleeachothersocloselyingeneralappearancethattheycannotbedistinguished。

  Justascertainspeciesandgroupsofspecies,whenpropagatedbyseed,aremorevariablethanotherspeciesorgenera,soitisinthecaseofcertainbud—varieties。Thus,theQueenofEnglandChrysanthemumhasproducedbythislatterprocessnolessthansix,andRollisson’sUniquePelargoniumfourdistinctvarieties;moss—roseshavealsoproducedseveralothermoss—

  roses。TheRosaceaehavevariedbybudsmorethananyothergroupofplants;butthismaybeinlargepartduetosomanymembershavingbeenlongcultivated;butwithinthissamegroup,thepeachhasoftenvariedbybuds,whilsttheappleandpear,bothgraftedtreesextensivelycultivated,haveafforded,asfarasIcanascertain,extremelyfewinstancesofbud—

  variation。

  Thelawofanalogousvariationholdsgoodwithvarietiesproducedbybuds,aswiththoseproducedfromseed:morethanonekindofrosehassportedintoamoss—rose;morethanonekindofcamelliahasassumedanhexagonalform;andatleastsevenoreightvarietiesofthepeachhaveproducednectarines。

  Thelawsofinheritanceseemtobenearlythesamewithseminalandbud—

  varieties。Weknowhowcommonlyreversioncomesintoplaywithboth,anditmayaffectthewhole,oronlysegmentsofaleaf,flower,orfruit。Whenthetendencytoreversionaffectsmanybudsonthesametree,itbecomescoveredwithdifferentkindsofleaves,flowers,orfruit;butthereisreasontobelievethatsuchfluctuatingvarietieshavegenerallyarisenfromseed。Itiswellknownthat,outofanumberofseedlingvarieties,sometransmittheircharactermuchmoretrulybyseedthanothers;sowithbud—varieties,someretaintheircharacterbysuccessivebudsmoretrulythanothers;ofwhichinstanceshavebeengivenwithtwokindsofvariegatedEuonymusandwithcertainkindsoftulipsandpelargoniums。

  Notwithstandingthesuddenproductionofbud—varieties,thecharactersthusacquiredaresometimescapableoftransmissionbyseminalreproduction:Mr。

  Rivershasfoundthatmoss—rosesgenerallyreproducethemselvesbyseed;

  andthemossycharacterhasbeentransferredbycrossingfromonespeciesofrosetoanother。TheBostonnectarine,whichappearedasabud—

  variation,producedbyseedacloselyalliednectarine。Ontheotherhand,seedlingsfromsomebud—variationshaveprovedvariabletoanextremedegree。(11/159。Carriere’ProductiondesVarietes’page39。)Wehavealsoheard,ontheauthorityofMr。Salter,thatseedstakenfromabranchwithleavesvariegatedthroughbud—variation,transmitthischaracterveryfeebly;whilstmanyplants,whichwerevariegatedasseedlings,transmitvariegationtoalargeproportionoftheirprogeny。

  AlthoughIhavebeenabletocollectagoodmanycasesofbud—variation,asshowninthepreviouslists,andmightprobably,bysearchingforeignhorticulturalworks,havecollectedverymanymorecases,yettheirtotalnumberisasnothingincomparisonwiththatofseminalvarieties。Withseedlingsraisedfromthemorevariablecultivatedplants,thevariationsarealmostinfinitelynumerous,buttheirdifferencesaregenerallyslight:

  onlyatlongintervalsoftimeastronglymarkedmodificationappears。Ontheotherhand,itisasingularandinexplicablefactthat,whenplantsvarybybuds,thevariations,thoughtheyoccurwithcomparativerarity,areoften,orevengenerally,stronglypronounced。Itstruckmethatthismightperhapsbeadelusion,andthatslightchangesoftenoccurredinbuds,butwereoverlookedornotrecordedfrombeingofnovalue。

  Accordingly,Iappliedtotwogreatauthoritiesonthissubject,namely,toMr。Riverswithrespecttofruit—trees,andtoMr。Salterwithrespecttoflowers。Mr。Riversisdoubtful,butdoesnotrememberhavingnoticedveryslightvariationsinfruit—buds。Mr。Salterinformsmethatwithflowerssuchdooccur,but,ifpropagated,theygenerallylosetheirnewcharacterinthefollowingyear;yetheconcurswithmethatbud—variationsusuallyatonceassumeadecidedandpermanentcharacter。Wecanhardlydoubtthatthisistherule,whenwereflectonsuchcasesasthatofthepeach,whichhasbeensocarefullyobserved,andofwhichsuchtriflingseminalvarietieshavebeenpropagated,yetthistreehasrepeatedlyproducedbybud—variationnectarines,andonlytwice(asfarasIcanlearn)anyothervariety,namely,theEarlyandLateGrosseMignonnepeaches;andthesedifferfromtheparent—treeinhardlyanycharacterexcepttheperiodofmaturity。

  Tomysurprise,IhearfromMr。Salterthathebringstheprincipleofselectiontobearonvariegatedplantspropagatedbybuds,andhasthusgreatlyimprovedandfixedseveralvarieties。Heinformsmethatatfirstabranchoftenproducesvariegatedleavesononesidealone,andthattheleavesaremarkedonlywithanirregularedgingorwithafewlinesofwhiteandyellow。Toimproveandfixsuchvarieties,hefindsitnecessarytoencouragethebudsatthebasesofthemostdistinctlymarkedleaves,andtopropagatefromthemalone。Byfollowingwithperseverancethisplanduringthreeorfoursuccessiveseasons,adistinctandfixedvarietycangenerallybesecured。

  Finally,thefactsgiveninthischapterproveinhowcloseandremarkableamannerthegermofafertilisedseedandthesmallcellularmassformingabud,resembleeachotherinalltheirfunctions——intheirpowerofinheritancewithoccasionalreversion,——andintheircapacityforvariationofthesamegeneralnature,inobediencetothesamelaws。Thisresemblance,orratheridentityofcharacter,isshowninthemoststrikingmannerbythefactthatthecellulartissueofonespeciesorvariety,whenbuddedorgraftedonanother,maygiverisetoabudhavinganintermediatecharacter。Wehaveseenthatvariabilitydoesnotdependonsexualgeneration,thoughmuchmorefrequentlyitsconcomitantthanofbudreproduction。Wehaveseenthatbud—variabilityisnotsolelydependentonreversionoratavismtolong—lostcharacters,ortothoseformerlyacquiredfromacross,butappearsoftentobespontaneous。Butwhenweaskourselveswhatisthecauseofanyparticularbud—variation,wearelostindoubt,beingdriveninsomecasestolooktothedirectactionoftheexternalconditionsoflifeassufficient,andinothercasestofeelaprofoundconvictionthatthesehaveplayedaquitesubordinatepart,ofnotmoreimportancethanthenatureofthesparkwhichignitesamassofcombustiblematter。

  CHAPTER1。XII。

  INHERITANCE。

  WONDERFULNATUREOFINHERITANCE。

  PEDIGREESOFOURDOMESTICATEDANIMALS。

  INHERITANCENOTDUETOCHANCE。

  TRIFLINGCHARACTERSINHERITED。

  DISEASESINHERITED。

  PECULIARITIESINTHEEYEINHERITED。

  DISEASESINTHEHORSE。

  LONGEVITYANDVIGOUR。

  ASYMMETRICALDEVIATIONSOFSTRUCTURE。

  POLYDACTYLISMANDREGROWTHOFSUPERNUMERARYDIGITSAFTERAMPUTATION。

  CASESOFSEVERALCHILDRENSIMILARLYAFFECTEDFROMNON—AFFECTEDPARENTS。

  WEAKANDFLUCTUATINGINHERITANCE:INWEEPINGTREES,INDWARFNESS,COLOUROF

  FRUITANDFLOWERS。

  COLOUROFHORSES。

  NON—INHERITANCEINCERTAINCASES。

  INHERITANCEOFSTRUCTUREANDHABITSOVERBORNEBYHOSTILECONDITIONSOF

  LIFE,BYINCESSANTLYRECURRINGVARIABILITY,ANDBYREVERSION。

  CONCLUSION。

  Thesubjectofinheritanceisanimmenseone,andhasbeentreatedbymanyauthors。Oneworkalone,’Del’HerediteNaturelle’byDr。ProsperLucas,runstothelengthof1562pages。Wemustconfineourselvestocertainpointswhichhaveanimportantbearingonthegeneralsubjectofvariation,bothwithdomesticandnaturalproductions。Itisobviousthatavariationwhichisnotinheritedthrowsnolightonthederivationofspecies,norisofanyservicetoman,exceptinthecaseofperennialplants,whichcanbepropagatedbybuds。

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