IntheexperimentsonthehybridHippeastrums，ifHerberthadfoundthatthepollenoftwoorthreekindsalonehadbeenmoreefficientoncertainkindsthantheirownpollen，itmighthavebeenarguedthatthese，fromtheirmixedparentage，hadaclosermutualaffinitythantheothers;butthisexplanationisinadmissible，forthetrialsweremadereciprocallybackwardsandforwardsonninedifferenthybrids;andacross，whicheverwaytaken，alwaysprovedhighlybeneficial。IcanaddastrikingandanalogouscasefromexperimentsmadebytheRev。A。Rawson，ofBromleyCommon，withsomecomplexhybridsofGladiolus。ThisskilfulhorticulturistpossessedanumberofFrenchvarieties，differingfromeachotheronlyinthecolourandsizeoftheflowers，alldescendedfromGandavensis，awell—knownoldhybrid，saidtobedescendedfromG。natalensisbythepollenofG。oppositiflorus。（17/86。Mr。D。Beatonin’JournalofHort。’1861page453。Lecoqhowever（’DelaFecond。’1862page369）statesthatthishybridisdescendedfromG。psittacinusandcardinalis;
butthisisopposedtoHerbert’sexperience，whofoundthattheformerspeciescouldnotbecrossed。）Mr。Rawson，afterrepeatedtrials，foundthatnoneofthevarietieswouldsetseedwiththeirownpollen，althoughtakenfromdistinctplantsofthesamevariety（whichhad，ofcourse，beenpropagatedbybulbs），butthattheyallseededfreelywithpollenfromanyothervariety。Togivetwoexamples:Ophirdidnotproduceacapsulewithitsownpollen，butwhenfertilisedwiththatofJanire，Brenchleyensis，VulcainandLinne，itproducedtenfinecapsules;butthepollenofOphirwasgood，forwhenLinnewasfertilisedbyitsevencapsuleswereproduced。Thislattervariety，ontheotherhand，wasutterlybarrenwithitsownpollen，whichwehaveseenwasperfectlyefficientonOphir。Altogether，Mr。Rawson，intheyear1861
fertilisedtwenty—sixflowersbornebyfourvarietieswithpollentakenfromothervarieties，andeverysingleflowerproducedafineseed—capsule;whereasfifty—twoflowersonthesameplants，fertilisedatthesametimewiththeirownpollen，didnotyieldasingleseed—capsule。Mr。Rawsonfertilised，insomecases，thealternateflowers，andinothercasesallthosedownonesideofthespike，withpollenofothervarieties，andtheremainingflowerswiththeirownpollen。Isawtheseplantswhenthecapsuleswerenearlymature，andtheircuriousarrangementatoncebroughtfullconvictiontothemindthatanimmenseadvantagehadbeenderivedfromcrossingthesehybrids。
Lastly，IhaveheardfromDr。E。Bornet，ofAntibes，whohasmadenumerousexperimentsincrossingthespeciesofCistus，buthasnotyetpublishedtheresults，that，whenanyofthesehybridsarefertile，theymaybesaidtobe，inregardtofunction，dioecious;\"fortheflowersarealwayssterilewhenthepistilisfertilisedbypollentakenfromthesameflowerorfromflowersonthesameplant。Buttheyareoftenfertileifpollenbeemployedfromadistinctindividualofthesamehybridnature，orfromahybridmadebyareciprocalcross。\"]
CONCLUSION。
......购买会员看全站小说，或者下载APP免费观看所有作品 点击立即下载，搜索"The Variation of Animals and Plants under Domestic",免费读到尾