孟德尔植物杂交实验论文1865年英文及中译.docx

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