variationtotheirordinaryfoliage。Thistendency，however，differsmuchinthevarietiesofeventhesamespecies;forinstance，thegolden—stripedvarietyofEuonymusjaponicus"isveryliabletorunbacktothegreen—
leaved，whilethesilver—stripedvarietyhardlyeverchanges。"（11/67。
’Gardener’sChron。’1844page86。）Ihaveseenavarietyoftheholly，withitsleaveshavingacentralyellowpatch，whichhadeverywherepartiallyrevertedtotheordinaryfoliage，sothatonthesamesmallbranchthereweremanytwigsofbothkinds。Inthepelargonium，andinsomeotherplants，variegationisgenerallyaccompaniedbysomedegreeofdwarfing，asiswellexemplifiedinthe"Dandy"pelargonium。Whensuchdwarfvarietiessportbackbybudsorsuckerstotheordinaryfoliage，thedwarfedstaturestillremains。（11/68。Ibid1861page963。）Itisremarkablethatplantspropagatedfrombrancheswhichhaverevertedfromvariegatedtoplainleaves（11/69。Ibid1861page433;’CottageGardener’1860page2。）donotalways（ornever，asoneobserverasserts）perfectlyresembletheoriginalplain—leavedplantfromwhichthevariegatedbrancharose:itseemsthataplant，inpassingbybud—variationfromplainleavestovariegated，andbackagainfromvariegatedtoplain，isgenerallyinsomedegreeaffectedsoastoassumeaslightlydifferentaspect。
BUD—VARIATIONBYSUCKERS，TUBERS，ANDBULBS。
Allthecaseshithertogivenofbud—variationinfruits，flowers，leaves，andshoots，havebeenconfinedtobudsonthestemsorbranches，withtheexceptionofafewcasesincidentallynoticedofvaryingsuckersintherose，pelargonium，andchrysanthemum。Iwillnowgiveafewinstancesofvariationinsubterraneanbuds，thatis，bysuckers，tubers，andbulbs;notthatthereisanyessentialdifferencebetweenbudsaboveandbeneaththeground。Mr。SalterinformsmethattwovariegatedvarietiesofPhloxoriginatedassuckers;butIshouldnothavethoughttheseworthmentioning，hadnotMr。Salterfound，afterrepeatedtrials，thathecouldnotpropagatethemby"root—joints，"whereas，thevariegatedTussilagofarfaracanthusbesafelypropagated（11/70。M。Lemoinequotedin’Gardener’sChronicle’1867page74haslatelyobservedthattheSymphytumwithvariegatedleavescannotbepropagatedbydivisionoftheroots。Healsofoundthatoutof500plantsofaPhloxwithstripedflowers，whichhadbeenpropagatedbyroot—division，onlysevenoreightproducedstripedflowers。SeealsoonstripedPelargoniums’Gardener’sChronicle’1867page1000。）;butthislatterplantmayhaveoriginatedasavariegatedseedling，whichwouldaccountforitsgreaterfixednessofcharacter。TheBarberry（Berberisvulgaris）offersananalogouscase;thereisawell—knownvarietywithseedlessfruit，whichcanbepropagatedbycuttingsorlayers;butsuckersalwaysreverttothecommonform，whichproducesfruitcontainingseeds。（11/71。Anderson’RecreationsinAgriculture’volume5page152。）Myfatherrepeatedlytriedthisexperiment，andalwayswiththesameresult。I
mayherementionthatmaizeandwheatsometimesproducenewvarietiesfromthestockorroot，asdoesthesugar—cane。（11/72。Forwheatsee’ImprovementoftheCereals’byP。Shirreff1873page47。Formaizeandsugar—caneCarriereibidpages40，42。Withrespecttothesugar—caneMr。
J。CaldwellofMauritiussays（’Gardener’sChronicle’1874page316）theRibboncanehashere"sportedintoaperfectlygreencaneandaperfectlyredcanefromthesamehead。Iverifiedthismyself，andsawatleast200
instancesinthesameplantation，andthefacthascompletelyupsetallourpreconceivedideasofthedifferenceofcolourbeingpermanent。Theconversionofastripedcaneintoagreencanewasnotuncommon，butthechangeintoaredcaneuniversallydisbelieved，andthatbotheventsshouldoccurinthesameplantincredible。Ifind，however，inFleischman’s’ReportonSugarCultivationinLouisianafor1848bytheAmericanPatentOffice，thecircumstanceismentioned，buthesaysheneversawithimself。"）
Turningnowtotubers:inthecommonPotato（Solanumtuberosum）asinglebudoreyesometimesvariesandproducesanewvariety;or，occasionally，andthisisamuchmoreremarkablecircumstance，alltheeyesinatubervaryinthesamemannerandatthesametime，sothatthewholetuberassumesanewcharacter。Forinstance，asingleeyeinatuberoftheoldFORTY—FOLDPOTATO，whichisapurplevariety，wasobserved（11/73。
’Gardener’sChronicle’1857page662。）tobecomewhite;thiseyewascutoutandplantedseparately，andthekindhassincebeenlargelypropagated。
KEMP’SPOTATOisproperlywhite，butaplantinLancashireproducedtwotuberswhichwerered，andtwowhichwerewhite;theredkindwaspropagatedintheusualmannerbyeyes，andkepttruetoitsnewcolour，and，beingfoundamoreproductivevariety，soonbecamewidelyknownunderthenameofTAYLOR’SFORTY—FOLD。（11/74。’Gard。Chronicle’1841page814。）
TheoldFORTY—FOLDPOTATO，asalreadystated，isapurplevariety;butaplantlongcultivatedonthesamegroundproduced，not，asinthecaseabovegiven，asinglewhiteeye，butawholewhitetuber，whichhassincebeenpropagatedandkeepstrue。（11/75。Ibid1857page613。）Severalcaseshavebeenrecordedoflargeportionsofwholerowsofpotatoesslightlychangingtheircharacter。（11/76。Ibid1857page679。SeealsoPhilips’Hist。ofVegetables’volume2page91forotherandsimilaraccounts。）
DahliaspropagatedbytubersunderthehotclimateofSt。Domingovarymuch;SirR。Schomburgkgivesthecaseofthe"Butterflyvariety，"whichthesecondyearproducedonthesameplant"doubleandsingleflowers;herewhitepetalsedgedwithmaroon;thereofauniformdeepmaroon。"（11/77。
’JournalofProc。Linn。Soc。’volume2Botanypage132。）Mr。Breealsomentionsaplant"whichboretwodifferentkindsofself—colouredflowers，aswellasathirdkindwhichpartookofbothcoloursbeautifullyintermixed。"（11/78。Loudon’s’Gardener’sMag。’volume81832page94。）
Anothercaseisdescribedofadahliawithpurpleflowerswhichboreawhiteflowerstreakedwithpurple。（11/79。’Gard。Chronicle’1850page536;
and1842page729。）
ConsideringhowlongandextensivelymanyBulbousplantshavebeencultivated，andhownumerousarethevarietiesproducedfromseed，theseplantshavenotperhapsvariedsomuchbyoffsets，——thatis，bytheproductionofnewbulbs，——asmighthavebeenexpected。WiththeHyacinth，however，severalinstanceshavebeengivenbyM。Carriere。Acasealsohasbeenrecordedofabluevarietywhichforthreesuccessiveyearsgaveoffsetsproducingwhiteflowerswitharedcentre。（11/80。’DesJacinthes’
etc。Amsterdam1768page122。）Anotherhyacinthbore（11/81。’Gardener’sChronicle’1845page212。）onthesametrussaperfectlypinkandaperfectlyblueflower。Ihaveseenabulbproducingatthesametimeonestalkortrusswithfineblueflowers，anotherwithfineredflowers，andathirdwithblueflowersononesideandredontheother;severaloftheflowersbeingalsolongitudinallystripedredandblue。
Mr。JohnScottinformsmethatin1862Imatophyllumminiatum，intheBotanicGardensofEdinburgh，threwupasuckerwhichdifferedfromthenormalform，intheleavesbeingtwo—rankedinsteadoffour—ranked。Theleaveswerealsosmaller，withtheuppersurfaceraisedinsteadofbeingchannelled。
InthepropagationofTULIPS，seedlingsareraised，calledselfsorbreeders，which，"consistofoneplaincolouronawhiteoryellowbottom。
These，beingcultivatedonadryandratherpoorsoil，becomebrokenorvariegatedandproducenewvarieties。Thetimethatelapsesbeforetheybreakvariesfromonetotwentyyearsormore，andsometimesthischangenevertakesplace。"（11/82。Loudon’s’EncyclopaediaofGardening’page1024。）Thebrokenorvariegatedcolourswhichgivevaluetoalltulipsareduetobud—variation;foralthoughtheBybloemensandsomeotherkindshavebeenraisedfromseveraldistinctbreeders，yetalltheBaguetsaresaidtohavecomefromasinglebreederorseedling。Thisbud—variation，inaccordancewiththeviewsofMM。VilmorinandVerlot（11/83。’ProductiondesVarietes’1865p。63。）isprobablyanattempttoreverttothatuniformcolourwhichisnaturaltothespecies。Atulip，however，whichhasalreadybecomebroken，whentreatedwithtoostrongmanure，isliabletoflushorlosebyasecondactofreversionitsvariegatedcolours。Somekinds，asImperatrixFlorum，aremuchmoreliablethanotherstoflushing;andMr。
Dicksonmaintains（11/84。’Gardener’sChronicle’1841page782;1842page55。）thatthiscannomorebeaccountedforthanthevariationofanyotherplant。HebelievesthatEnglishgrowers，fromcareinchoosingseedfrombrokenflowersinsteadoffromplainflowers，havetoacertainextentdiminishedthetendencyinflowersalreadybrokentoflushingorsecondaryreversion。Irisxiphium，accordingtoM。Carriere（page65），behavesinnearlythesamemanner，asdosomanytulips。
DuringtwoconsecutiveyearsalltheearlyflowersinabedofTigridiaconchiflora（11/85。’Gardener’sChron。’1849page565。）resembledthoseoftheoldT。pavonia;butthelaterflowersassumedtheirpropercolouroffineyellow，spottedwithcrimson。Anapparentlyauthenticaccounthasbeenpublished（11/86。’Transact。Lin。Soc。’volume2page354。）oftwoformsofHemerocallis，whichhavebeenuniversallyconsideredasdistinctspecies，changingintoeachother;fortherootsofthelarge—floweredtawnyH。
fulva，beingdividedandplantedinadifferentsoilandplace，producedthesmall—floweredH。flava，aswellassomeintermediateforms。Itisdoubtfulwhethersuchcasesastheselatter，aswellasthe"flushing"ofbrokentulipsandthe"running"ofparticolouredcarnations，——thatis，theirmoreorlesscompletereturntoauniformtint，——oughttobeclassedunderbud—variation，oroughttoberetainedforthechapterinwhichI
treatofthedirectactionoftheconditionsoflifeonorganicbeings。
Thesecases，however，havethismuchinbud—variation，thatthechangeiseffectedthroughbudsandnotthroughseminalreproduction。But，ontheotherhand，thereisthisdifference——thatinordinarycasesofbud—
variation，onebudalonechanges，whilstintheforegoingcasesallthebudsonthesameplantweremodifiedtogether。Withthepotato，wehaveseenanintermediatecase，foralltheeyesinonetubersimultaneouslychangedtheircharacter。
Iwillconcludewithafewalliedcases，whichmayberankedeitherunderbud—variation，orunderthedirectactionoftheconditionsoflife。WhenthecommonHepaticaistransplantedfromitsnativewoods，theflowerschangecolour，evenduringthefirstyear。（11/87。Godron’Del’Espece’
tome2page84。）ItisnotoriousthattheimprovedvarietiesoftheHeartsease（Violatricolor），whentransplanted，oftenproduceflowerswidelydifferentinsize，form，andcolour:forinstance，Itransplantedalargeuniformly—coloureddarkpurplevariety，whilstinfullflower，anditthenproducedmuchsmaller，moreelongatedflowers，withthelowerpetalsyellow;theseweresucceededbyflowersmarkedwithlargepurplespots，andultimately，towardstheendofthesamesummer，bytheoriginallargedarkpurpleflowers。Theslightchangeswhichsomefruit—treesundergofrombeinggraftedandregraftedonvariousstocks（11/88。M。Carrierehaslatelydescribedinthe’RevueHorticole’December1，1866page457，anextraordinarycase。HetwiceinsertedgraftsoftheAriavestitaonthorn—
trees（epines）growinginpots;andthegrafts，astheygrew，producedshootswithbark，buds，leaves，petioles，petals，andflower—stalks，allwidelydifferentfromthoseoftheAria。Thegraftedshootswerealsomuchhardier，andfloweredearlier，thanthoseontheungraftedAria。）wereconsideredbyAndrewKnight（11/89。’Transact。Hort。Soc。’volume2page160。）ascloselyalliedto"sportingbranches，"orbud—variations。Again，wehavethecaseofyoungfruit—treeschangingtheircharacterastheygrowold;seedlingpears，forinstance，losewithagetheirspinesandimproveintheflavouroftheirfruit。Weepingbirch—trees，whengraftedonthecommonvariety，donotacquireaperfectpenduloushabituntiltheygrowold:ontheotherhand，Ishallhereaftergivethecaseofsomeweepingasheswhichslowlyandgraduallyassumedanuprighthabitofgrowth。Allsuchchanges，dependentonage，maybecomparedwiththechanges，alludedtointhelastchapter，whichmanytreesnaturallyundergo;asinthecaseoftheDeodarandCedarofLebanon，whichareunlikeinyouth，whilsttheycloselyresembleeachotherinoldage;andaswithcertainoaks，andwithsomevarietiesofthelimeandhawthorn。（11/90。ForthecasesofoaksseeAlph。DeCandollein’Bibl。Univers。’GenevaNovember1862;forlimesetc。
Loudon’s’Gard。Mag。’volume111835page503。）]
GRAFT—HYBRIDS。
BeforegivingasummaryonBud—variationIwilldiscusssomesingularandanomalouscases，whicharemoreorlesscloselyrelatedtothissamesubject。IwillbeginwiththefamouscaseofAdam’slaburnumorCytisusadami，aformorhybridintermediatebetweentwoverydistinctspecies，namely，C。laburnumandpurpureus，thecommonandpurplelaburnum;butasthistreehasoftenbeendescribed，IwillbeasbriefasIcan。
[ThroughoutEurope，indifferentsoilsandunderdifferentclimates，branchesonthistreehaverepeatedlyandsuddenlyrevertedtothetwoparentspeciesintheirflowersandleaves。Tobeholdmingledonthesametreetuftsofdingy—red，brightyellow，andpurpleflowers，borneonbrancheshavingwidelydifferentleavesandmannerofgrowth，isasurprisingsight。Thesameracemesometimesbearstwokindsofflowers;andIhaveseenasingleflowerexactlydividedintohalves，onesidebeingbrightyellowandtheotherpurple;sothatonehalfofthestandard—petalwasyellowandoflargersize，andtheotherhalfpurpleandsmaller。Inanotherflowerthewholecorollawasbrightyellow，butexactlyhalfthecalyxwaspurple。Inanother，oneofthedingy—redwing—petalshadanarrowbrightyellowstripeonit;andlastly，inanotherflower，oneofthestamens，whichhadbecomeslightlyfoliaceous，washalfyellowandhalfpurple;sothatthetendencytosegregationofcharacterorreversionaffectsevensinglepartsandorgans。（11/91。ForanalogousfactsseeBraun’Rejuvenescence’in’RaySoc。Bot。Mem。’1853page320;and’Gardener’sChronicle’1842page397;alsoBraunin’SitzungsberichtederGes。
naturforschenderFreunde’June1873page63。）Themostremarkablefactaboutthistreeisthatinitsintermediatestate，evenwhengrowingnearbothparent—species，itisquitesterile;butwhentheflowersbecomepureyelloworpurepurpletheyyieldseed。Ibelievethatthepodsfromtheyellowflowersyieldafullcomplementofseed;theycertainlyyieldalargernumber。TwoseedlingsraisedbyMr。Herbertfromsuchseed（11/92。
’JournalofHort。Soc。’volume21847page100。）exhibitedapurpletingeonthestalksoftheirflowers;butseveralseedlingsraisedbymyselfresembledineverycharacterthecommonlaburnum，withtheexceptionthatsomeofthemhadremarkablylongracemes:theseseedlingswereperfectlyfertile。Thatsuchpurityofcharacterandfertilityshouldbesuddenlyreacquiredfromsohybridisedandsterileaformisanastonishingphenomenon。ThebrancheswithpurpleflowersappearatfirstsightexactlytoresemblethoseofC。purpureus;butoncarefulcomparisonIfoundthattheydifferedfromthepurespeciesintheshootsbeingthicker，theleavesalittlebroader，andtheflowersslightlyshorter，withthecorollaandcalyxlessbrightlypurple:thebasalpartofthestandard—petalalsoplainlyshowedatraceoftheyellowstain。Sothattheflowers，atleastinthisinstance，hadnotperfectlyrecoveredtheirtruecharacter;andinaccor...完整阅读请扫描二维码下载丁香书院APP免费看：