孟德尔植物杂交实验论文1865年英文及中译.docx
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孟德尔植物杂交实验论文1865年英文及中译.docx
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孟德尔植物杂交实验论文1865年英文及中译
Mendel'sPaperinEnglish
ExperimentsinPlantHybridization(1865)
byGregorMendel
ReadatthemeetingsofFebruary8th,andMarch8th,1865
[1]IntroductoryRemarks
Experienceofartificialfertilization,suchasiseffectedwithornamentalplantsinordertoobtainnewvariationsincolor,hasledtotheexperimentswhichwillherebediscussed.Thestrikingregularitywithwhichthesamehybridformsalwaysreappearedwheneverfertilizationtookplacebetweenthesamespeciesinducedfurtherexperimentstobeundertaken,theobjectofwhichwastofollowupthedevelopmentsofthehybridsintheirprogeny.
Tothisobjectnumerouscarefulobservers,suchasKölreuter,Gärtner,Herbert,Lecoq,Wichuraandothers,havedevotedapartoftheirliveswithinexhaustibleperseverance.GärtnerespeciallyinhisworkDieBastarderzeugungimPflanzenreiche,hasrecordedveryvaluableobservations;andquiterecentlyWichurapublishedtheresultsofsomeprofoundinvestigationsintothehybridsoftheWillow.That,sofar,nogenerallyapplicablelawgoverningtheformationanddevelopmentofhybridshasbeensuccessfullyformulatedcanhardlybewonderedatbyanyonewhoisacquaintedwiththeextentofthetask,andcanappreciatethedifficultieswithwhichexperimentsofthisclasshavetocontend.Afinaldecisioncanonlybearrivedatwhenweshallhavebeforeustheresultsofdetailedexperimentsmakeonplantsbelongingtothemostdiverseorders.
Thosewhosurveytheworkdoneinthisdepartmentwillarriveattheconvictionthatamongallthenumerousexperimentsmade,notonehasbeencarriedouttosuchanextentandinsuchawayastomakeitpossibletodeterminethenumberofdifferentformsunderwhichtheoffspringofthehybridsappear,ortoarrangetheseformswithcertaintyaccordingtotheirseparategenerations,ordefinitelytoascertaintheirstatisticalrelations.
Itrequiresindeedsomecouragetoundertakealaborofsuchfar-reachingextent;thisappears,however,tobetheonlyrightwaybywhichwecanfinallyreachthesolutionofaquestiontheimportanceofwhichcannotbeoverestimatedinconnectionwiththehistoryoftheevolutionoforganicforms.
Thepapernowpresentedrecordstheresultsofsuchadetailedexperiment.Thisexperimentwaspracticallyconfinedtoasmallplantgroup,andisnow,aftereightyears'pursuit,concludedinallessentials.Whethertheplanuponwhichtheseparateexperimentswereconductedandcarriedoutwasthebestsuitedtoattainthedesiredendislefttothefriendlydecisionofthereader.
[2]SelectionoftheExperimentalPlants
Thevalueandutilityofanyexperimentaredeterminedbythefitnessofthematerialtothepurposeforwhichitisused,andthusinthecasebeforeusitcannotbeimmaterialwhatplantsaresubjectedtoexperimentandinwhatmannersuchexperimentisconducted.
Theselectionoftheplantgroupwhichshallserveforexperimentsofthiskindmustbemadewithallpossiblecareifitbedesiredtoavoidfromtheoutseteveryriskofquestionableresults.
Theexperimentalplantsmustnecessarily:
1.Possessconstantdifferentiatingcharacteristics.
2.Thehybridsofsuchplantsmust,duringthefloweringperiod,beprotectedfromtheinfluenceofallforeignpollen,orbeeasilycapableofsuchprotection.
Thehybridsandtheiroffspringshouldsuffernomarkeddisturbanceintheirfertilityinthesuccessivegenerations.
Accidentalimpregnationbyforeignpollen,ifitoccurredduringtheexperimentsandwerenotrecognized,wouldleadtoentirelyerroneousconclusions.Reducedfertilityorentiresterilityofcertainforms,suchasoccursintheoffspringofmanyhybrids,wouldrendertheexperimentsverydifficultorentirelyfrustratethem.Inordertodiscovertherelationsinwhichthehybridformsstandtowardseachotherandalsotowardstheirprogenitorsitappearstobenecessarythatallmemberoftheseriesdevelopedineachsuccessivegenerationsshouldbe,withoutexception,subjectedtoobservation.
AttheveryoutsetspecialattentionwasdevotedtotheLeguminosaeonaccountoftheirpeculiarfloralstructure.ExperimentswhichweremadewithseveralmembersofthisfamilyledtotheresultthatthegenusPisumwasfoundtopossessthenecessaryqualifications.
Somethoroughlydistinctformsofthisgenuspossesscharacterswhichareconstant,andeasilyandcertainlyrecognizable,andwhentheirhybridsaremutuallycrossedtheyyieldperfectlyfertileprogeny.Furthermore,adisturbancethroughforeignpollencannoteasilyoccur,sincethefertilizingorgansarecloselypackedinsidethekeelandtheanthersburstwithinthebud,sothatthestigmabecomescoveredwithpollenevenbeforethefloweropens.Thiscircumstanceisespeciallyimportant.Asadditionaladvantagesworthmentioning,theremaybecitedtheeasycultureoftheseplantsintheopengroundandinpots,andalsotheirrelativelyshortperiodofgrowth.Artificialfertilizationiscertainlyasomewhatelaborateprocess,butnearlyalwayssucceeds.Forthispurposethebudisopenedbeforeitisperfectlydeveloped,thekeelisremoved,andeachstamencarefullyextractedbymeansofforceps,afterwhichthestigmacanatoncebedustedoverwiththeforeignpollen.
Inall,34moreorlessdistinctvarietiesofPeaswereobtainedfromseveralseedsmenandsubjectedtoatwoyear'strial.Inthecaseofonevarietytherewerenoticed,amongalargernumberofplantsallalike,afewformswhichweremarkedlydifferent.These,however,didnotvaryinthefollowingyear,andagreedentirelywithanothervarietyobtainedfromthesameseedsman;theseedswerethereforedoubtlessmerelyaccidentallymixed.Alltheothervarietiesyieldedperfectlyconstantandsimilaroffspring;atanyrate,noessentialdifferencewasobservedduringtwotrialyears.Forfertilization22ofthesewereselectedandcultivatedduringthewholeperiodoftheexperiments.Theyremainedconstantwithoutanyexception.
Theirsystematicclassificationisdifficultanduncertain.Ifweadoptthestrictestdefinitionofaspecies,accordingtowhichonlythoseindividualsbelongtoaspecieswhichunderpreciselythesamecircumstancesdisplaypreciselysimilarcharacters,notwoofthesevarietiescouldbereferredtoonespecies.Accordingtotheopinionofexperts,however,themajoritybelongtothespeciesPisumsativum;whiletherestareregardedandclassed,someassub-speciesofP.sativum,andsomeasindependentspecies,suchasP.quadratum,P.saccharatum,andP.umbellatum.Thepositions,however,whichmaybeassignedtotheminaclassificatorysystemarequiteimmaterialforthepurposesoftheexperimentsinquestion.Ithassofarbeenfoundtobejustasimpossibletodrawasharplinebetweenthehybridsofspeciesandvarietiesasbetweenspeciesandvarietiesthemselves.
[3]DivisionandArrangementoftheExperiments
Iftwoplantswhichdifferconstantlyinoneorseveralcharactersbecrossed,numerousexperimentshavedemonstratedthatthecommoncharactersaretransmittedunchangedtothehybridsandtheirprogeny;buteachpairofdifferentiatingcharacters,ontheotherhand,uniteinthehybridtoformanewcharacter,whichintheprogenyofthehybridisusuallyvariable.Theobjectoftheexperimentwastoobservethesevariationsinthecaseofeachpairofdifferentiatingcharacters,andtodeducethelawaccordingtowhichtheyappearinsuccessivegenerations.Theexperimentresolvesitselfthereforeintojustasmanyseparateexperimentsarethereareconstantlydifferentiatingcharacterspresentedintheexperimentalplants.
ThevariousformsofPeasselectedforcrossingshoweddifferencesinlengthandcolorofthestem;inthesizeandformoftheleaves;intheposition,color,sizeoftheflowers;inthelengthoftheflowerstalk;inthecolor,form,andsizeofthepods;intheformandsizeoftheseeds;andinthecoloroftheseed-coatsandofthealbumen[cotyledons].Someofthecharactersnoteddonotpermitofasharpandcertainseparation,sincethedifferenceisofa"moreorless"nature,whichisoftendifficulttodefine.Suchcharacterscouldnotbeutilizedfortheseparateexperiments;thesecouldonlybeappliedtocharacterswhichstandoutclearlyanddefinitelyintheplants.Lastly,theresultmustshowwhetherthey,intheirentirety,observearegularbehaviorintheirhybridunions,andwhetherfromthesefactsanyconclusioncanbereachedregardingthosecharacterswhichpossessasubordinatesignificanceinthetype.
Thecharacterswhichwereselectedforexperimentrelate:
1.Tothedifferenceintheformoftheripeseeds.Theseareeitherroundorroundish,thedepressions,ifany,occuronthesurface,beingalwaysonlyshallow;ortheyareirregularlyangularanddeeplywrinkled(P.quadratum).
2.Tothedifferenceinthecoloroftheseedalbumen(endosperm).Thealbumenoftheripeseedsiseitherpaleyellow,brightyellowandorangecolored,oritpossessesamoreorlessintensegreentint.Thisdifferenceofcoloriseasilyseenintheseedsastheircoatsaretransparent.
3.Tothedifferenceinthecoloroftheseed-coat.Thisiseitherwhite,withwhichcharacterwhiteflowersareconstantlycorrelated;oritisgray,gray-brown,leather-brown,withorwithoutvioletspotting,inwhichcasethecolorofthestandardsisviolet,thatofthewingspurple,andthestemintheaxilsoftheleavesisofareddishtint.Thegrayseed-coatsbecomedarkbrowninboilingwater.
4.Tothedifferenceintheformoftheripepods.Theseareeithersimplyinflated,notcontractedinplaces;ortheyaredeeplyconstrictedbetweentheseedsandmoreorlesswrinkled(P.saccharatum).
5.Tothedifference
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