Soc。Bot。’1862page94。）;andtheseareplantswhichfloristsspeakofasnevercomingtruebyseed:butifcarebetakentopreventcrossing，neitherspeciesisbyanymeansveryinconstant，incolour;thusIraisedtwenty—threeplantsfromapurpleprimrose，fertilisedbyMr。J。Scottwithitspollen，andeighteencameuppurpleofdifferentshades，andonlyfiverevertedtotheordinaryyellowcolour:again，Iraisedtwentyplantsfromabright—redcowslip，similarlytreatedbyMr。Scott，andeveryoneperfectlyresembleditsparentincolour，aslikewisedid，withtheexceptionofasingleplant，72grandchildren。Evenwiththemostvariableflowers，itisprobablethateachdelicateshadeofcolourmightbepermanentlyfixedsoastobetransmittedbyseed，bycultivationinthesamesoil，bylong—continuedselection，andespeciallybythepreventionofcrosses。Iinferthisfromcertainannuallarkspurs（Delphiniumconsolidaandajacis），ofwhichcommonseedlingspresentagreaterdiversityofcolourthananyotherplantknowntome;yetonprocuringseedoffivenamedGermanvarietiesofD。consolida，onlynineplantsoutofninety—fourwerefalse;andtheseedlingsofsixvarietiesofD。ajacisweretrueinthesamemanneranddegreeaswiththestocksabovedescribed。A
distinguishedbotanistmaintainsthattheannualspeciesofDelphiniumarealwaysself—fertilised;thereforeImaymentionthatthirty—twoflowersonabranchofD。consolida，enclosedinanet，yieldedtwenty—sevencapsules，withanaverageof17。2seedineach;whilstfiveflowers，underthesamenet，whichwereartificiallyfertilised，inthesamemannerasmustbeeffectedbybeesduringtheirincessantvisits，yieldedfivecapsuleswithanaverageof35。2fineseed;andthisshowsthattheagencyofinsectsisnecessaryforthefullfertilityofthisplant。Analogousfactscouldbegivenwithrespecttothecrossingofmanyotherflowers，suchascarnations，etc。，ofwhichthevarietiesfluctuatemuchincolour。
Aswithflowers，sowithourdomesticatedanimals，nocharacterismorevariablethancolour，andprobablyinnoanimalmoresothanwiththehorse。Yet，withalittlecareinbreeding，itappearsthatracesofanycolourmightsoonbeformed。Hofackergivestheresultofmatchingtwohundredandsixteenmaresoffourdifferentcolourswithlike—colouredstallions，withoutregardtothecolouroftheirancestors;andofthetwohundredandsixteencoltsborn，elevenalonefailedtoinheritthecolouroftheirparents:AutenriethandAmmonassertthat，aftertwogenerations，coltsofauniformcolourareproducedwithcertainty。（12/50。Hofacker’UeberdieEigenschaften’etc。s。10。）]
Inafewrarecasespeculiaritiesfailtobeinherited，apparentlyfromtheforceofinheritancebeingtoostrong。Ihavebeenassuredbybreedersofthecanary—birdthattogetagoodjonquil—colouredbirditdoesnotanswertopairtwojonquils，asthecolourthencomesouttoostrong，orisevenbrown;butthisstatementisdisputedbyotherbreeders。Soagain，iftwocrestedcanariesarepaired，theyoungbirdsrarelyinheritthischaracter（12/51。Bechstein’Naturgesch。Deutschlands’b。4s。462。Mr。Brent，agreatbreederofcanaries，informsmethathebelievesthatthesestatementsarecorrect。）:forincrestedbirdsanarrowspaceofbareskinisleftonthebackofthehead，wherethefeathersareup—turnedtoformthecrest，and，whenbothparentsarethuscharacterised，thebarenessbecomesexcessive，andthecrestitselffailstobedeveloped。Mr。Hewitt，speakingofLacedSebrightBantams，says（12/52。’ThePoultryBook’byW。B。
Tegetmeier1866page245。）that，"whythisshouldbesoIknownot，butI
amconfidentthatthosethatarebestlacedfrequentlyproduceoffspringveryfarfromperfectintheirmarkings，whilstthoseexhibitedbymyself，whichhavesooftenprovedsuccessful，werebredfromtheunionofheavily—
lacedbirdswiththosethatwerescarcelysufficientlylaced。"
Itisasingularfactthat，althoughseveraldeaf—mutesoftenoccurinthesamefamily，andthoughtheircousinsandotherrelationsareofteninthesamecondition，yettheirparentsarerarelydeaf—mutes。Togiveasingleinstance:notonescholaroutof148，whowereatthesametimeintheLondonInstitution，wasthechildofparentssimilarlyaffected。Soagain，whenamaleorfemaledeaf—mutemarriesasoundperson，theirchildrenaremostrarelyaffected:inIreland，outof203childrenthusproducedonealonewasmute。Evenwhenbothparentshavebeendeaf—mutes，asinthecaseofforty—onemarriagesintheUnitedStatesandofsixinIreland，onlytwodeafanddumbchildrenwereproduced。Mr。Sedgwick（12/53。’BritishandForeignMed。—Chirurg。Review’July1861pages200—204。Mr。Sedgwickhasgivensuchfulldetailsonthissubject，withamplereferences，thatIneedrefertonootherauthorities），incommentingonthisremarkableandfortunatefailureinthepoweroftransmissioninthedirectline，remarksthatitmaypossiblybeowingto"excesshavingreversedtheactionofsomenaturallawindevelopment。"Butitissaferinthepresentstateofourknowledgetolookatthewholecaseassimplyunintelligible。
Althoughmanycongenitalmonstrositiesareinherited，ofwhichexampleshavealreadybeengiven，andtowhichmaybeaddedthelatelyrecordedcaseofthetransmissionduringacenturyofhare—lipwithacleft—palateinthewriter’sownfamily（12/54。Mr。Sproulein’BritishMedicalJournal’April18，1863。）yetothermalformationsarerarelyorneverinherited。Oftheselattercases，manyareprobablyduetoinjuriesinthewomboregg，andwouldcomeundertheheadofnon—inheritedinjuriesormutilations。Withplants，alongcatalogueofinheritedmonstrositiesofthemostseriousanddiversifiednaturecouldeasilybegiven;andwithplants，thereisnoreasontosupposethatmonstrositiesarecausedbydirectinjuriestotheseedorembryo。
Withrespecttotheinheritanceofstructuresmutilatedbyinjuriesoralteredbydisease，itwasuntillatelydifficulttocometoanydefiniteconclusion。Somemutilationshavebeenpractisedforavastnumberofgenerationswithoutanyinheritedresult。Godronremarks（12/55。’Del’Espece’tome21859page299。）thatdifferentracesofmanhavefromtimeimmemorialknockedouttheirupperincisors，cutoffjointsoftheirfingers，madeholesofimmensesizethroughthelobesoftheirearsorthroughtheirnostrils，tatooedthemselves，madedeepgashesinvariouspartsoftheirbodies，andthereisnoreasontosupposethatthesemutilationshaveeverbeeninherited。（12/56。NeverthelessMr。Wetherellstates，’Nature’December1870page168，thatwhenhevisitedfifteenyearsagotheSiouxIndians，hewasinformed"byaphysician，whohaspassedmuchofhistimewiththesetribes，thatsometimesachildwasbornwiththesemarks。ThiswasconfirmedbytheU。S。GovernmentIndianAgent。"）Adhesionsduetoinflammationandpitsfromthesmall—pox（andformerlymanyconsecutivegenerationsmusthavebeenthuspitted）arenotinherited。WithrespecttoJews，IhavebeenassuredbythreemedicalmenoftheJewishfaiththatcircumcision，whichhasbeenpractisedforsomanyages，hasproducednoinheritedeffect。Blumenbach，however，asserts（12/57。
’Philosoph。Mag。’volume41799page5。）thatJewsareoftenborninGermanyinaconditionrenderingcircumcisiondifficult，sothatanameisgiventhemsignifying"borncircumcised;"andProfessorPreyerinformsmethatthisisthecaseinBonn，suchchildrenbeingconsideredthespecialfavouritesofJehovah。IhavealsoheardfromDr。A。Newman，ofGuy’sHospital，ofthegrandsonofacircumcisedJew，thefathernothavingbeencircumcised，inasimilarcondition。Butitispossiblethatallthesecasesmaybeaccidentalcoincidence，forSirJ。Pagethasseenfivesonsofaladyandonesonofhersisterwithadherentprepuces;andoneoftheseboyswasaffectedinamanner"whichmightbeconsideredlikethatcommonlyproducedbycircumcision;"yettherewasnosuspicionofJewishbloodinthefamilyofthesetwosisters。CircumcisionispractisedbyMahomedans，butatamuchlateragethanbyJews;andDr。Riedel，AssistantResidentinNorthCelebes，writestomethattheboystheregonakeduntilfromsixtotenyearsold;andhehasobservedthatmanyofthem，thoughnotall，havetheirprepucesmuchreducedinlength，andthisheattributestotheinheritedeffectsoftheoperation。Inthevegetablekingdomoaksandothertreeshavebornegallsfromprimevaltimes，yettheydonotproduceinheritedexcrescences;andmanyothersuchfactscouldbeadduced。
Notwithstandingtheaboveseveralnegativecases，wenowpossessconclusiveevidencethattheeffectsofoperationsaresometimesinherited。Dr。Brown—
Sequard（12/58。’Proc。RoyalSoc。’volume10page297。’CommunicationtotheBrit。Assoc。’1870。’TheLancet’January1875page7。Theextractsarefromthislastpaper。ItappearsthatObersteiner’Stricker’sMed。
Jahrbucher’1875No。2hasconfirmedBrown—Sequard’sobservations。）givesthefollowingsummaryofhisobservationsonguinea—pigs;andthissummaryissoimportantthatIwillquotethewhole:——
["1st。Appearanceofepilepsyinanimalsbornofparentshavingbeenrenderedepilepticbyaninjurytothespinalcord。
"2nd。Appearanceofepilepsyalsoinanimalsbornofparentshavingbeenrenderedepilepticbythesectionofthesciaticnerve。
"3rd。Achangeintheshapeoftheearinanimalsbornofparentsinwhichsuchachangewastheeffectofadivisionofthecervicalsympatheticnerve。
"4th。Partialclosureoftheeyelidsinanimalsbornofparentsinwhichthatstateoftheeyelidshadbeencausedeitherbythesectionofthecervicalsympatheticnerveortheremovalofthesuperiorcervicalganglion。
"5th。Exophthalmiainanimalsbornofparentsinwhichaninjurytotherestiformbodyhadproducedthatprotrusionoftheeyeball。ThisinterestingfactIhavewitnessedagoodmanytimes，andIhaveseenthetransmissionofthemorbidstateoftheeyecontinuethroughfourgenerations。Intheseanimals，modifiedbyheredity，thetwoeyesgenerallyprotruded，althoughintheparentsusuallyonlyoneshowedexophthalmia，thelesionhavingbeenmadeinmostcasesonlyononeofthecorporarestiformia。
"6th。Haematomaanddrygangreneoftheearsinanimalsbornofparentsinwhichtheseear—alterationshadbeencausedbyaninjurytotherestiformbodynearthenibofthecalamus。
"7th。Absenceoftwotoesoutofthethreeofthehindleg，andsometimesofthethree，inanimalswhoseparentshadeatenuptheirhind—legtoeswhichhadbecomeanaestheticfromasectionofthesciaticnervealone，orofthatnerveandalsoofthecrural。Sometimes，insteadofcompleteabsenceofthetoes，onlyapartofoneortwoorthreewasmissingintheyoung，althoughintheparentnotonlythetoesbutthewholefootwasabsent（partlyeatenoff，partlydestroyedbyinflammation，ulceration，organgrene）。
"8th。Appearanceofvariousmorbidstatesoftheskinandhairoftheneckandfaceinanimalsbornofparentshavinghadsimilaralterationsinthesameparts，aseffectsofaninjurytothesciaticnerve。"]
ItshouldbeespeciallyobservedthatBrown—Sequardhasbredduringthirtyyearsmanythousandguinea—pigsfromanimalswhichhadnotbeenoperatedupon，andnotoneofthesemanifestedtheepileptictendency。Norhasheeverseenaguinea—pigbornwithouttoes，whichwasnottheoffspringofparentswhichhadgnawedofftheirowntoesowingtothesciaticnervehavingbeendivided。Ofthislatterfactthirteeninstanceswerecarefullyrecorded，andagreaternumberwereseen;yetBrown—Sequardspeaksofsuchcasesasoneoftherarerformsofinheritance。Itisastillmoreinterestingfact——
["Thatthesciaticnerveinthecongenitallytoelessanimalhasinheritedthepowerofpassingthroughallthedifferentmorbidstateswhichhaveoccurredinoneofitsparentsfromthetimeofthedivisiontillafteritsreunionwiththeperiphericend。Itisnotthereforesimplythepowerofperforminganactionwhichisinherited，butthepowerofperformingawholeseriesofactions，inacertainorder。"]
InmostofthecasesofinheritancerecordedbyBrown—Sequardonlyoneofthetwoparentshadbeenoperateduponandwasaffected。Heconcludesbyexpressinghisbeliefthat"whatistransmittedisthemorbidstateofthenervoussystem，"duetotheoperationperformedontheparents。
WiththeloweranimalsDr。ProsperLucashascollectedalonglistofinheritedinjuries。Afewinstanceswillsuffice。Acowlostahornfromanaccidentwithconsequentsuppuration，andsheproducedthreecalveswhichwerehornlessonthesamesideofthehead。Withthehorse，thereseemshardlyadoubtthatexostosesonthelegs，causedbytoomuchtravellingonhardroads，areinherited。Blumenbachrecordsthecaseofamanwhohadhislittlefingerontherighthandalmostcutoff，andwhichinconsequencegrewcrooked，andhissonshadthesamefingeronthesamehandsimilarlycrooked。Asoldier，fifteenyearsbeforehismarriage，losthislefteyefrompurulentophthalmia，andhistwosonsweremicrophthalmiconthesameside。（12/59。ThislastcaseisquotedbyMr。Sedgwickin’BritishandForeignMedico—Chirurg。Review’April，1861page484。ForBlumenbachseeabove—citedpaper。SeealsoDr。P。Lucas’Traitedel’Hered。Nat。’tome2
page492。Also’Transact。Linn。Soc。’volume9page323。SomecuriouscasesaregivenbyMr。Bakerinthe’Veterinary’volume13page723。Anothercuriouscaseisgiveninthe’AnnalesdesScienc。Nat。’1stseries，tome11
page324。）Inallcasesinwhichaparenthashadanorganinjuredononeside，andtwoormoreoftheoffspringarebornwiththesameorganaffectedonthesameside，thechancesagainstmerecoincidencearealmostinfinitelygreat。Evenwhenonlyasinglechildisbornhavingexactlythesamepartofthebodyaffectedasthatofhisinjuredparent，thechancesagainstcoincidencearegreat;andProfessorRollestonhasgivenmetwosuchcaseswhichhavefallenunderhisownobservation，——namelyoftwomen，oneofwhomhadhiskneeandtheotherhischeekseverelycut，andbothhadchildrenbornwithexactlythesamespotmarkedorscarred。Manyinstanceshavebeenrecordedofcats，dogs，andhorses，whichhavehadtheirtails，legs，etc。，amputatedorinjured，producingoffspringwiththesamepartsill—formed;butasitisnotveryrareforsimilarmalformationstoappearspontaneously，allsuchcasesmaybeduetocoincidence。Itis，however，anargumentontheothersidethat"undertheoldexciselawstheshepherd—dogwasonlyexemptfromtaxwhenwithoutatail，andforthisreasonitwasalwaysremoved"（12/60。’TheDog’byStonehenge1867page118。）;andtherestillexistbreedsoftheshepherd—dogwhicharealwaysborndestituteofatail。Finally，itmustbeadmitted，moreespeciallysincethepublicationofBrown—Sequard’sobservations，thattheeffectsofinjuries，especiallywhenfollowedbydisease，orperhapsexclusivelywhenthusfollowed，areoccasionallyinherited。（12/61。TheMot—mothabituallybitesthebarbsoffthemiddlepartofthetwocentraltail—feathers，andasthebarbsarecongenitallysomewhatreducedonthesamepartofthesefeathers，itseemsextremelyprobable，asMr。Salvinremarks，’Proc。Zoolog。Soc。’1873page429，thatthisisduetotheinheritedeffectsoflong—continuedmutilation。）
CAUSESOFNON—INHERITANCE。
Alargenumberofcasesofnon—inheritanceareintelligibleontheprinciple，thatastrongtendencytoinheritancedoesexist，butthatitisoverbornebyhostileorunfavourableconditionsoflife。Noonewouldexpectthatourimprovedpigs，ifforcedduringseveralgenerationstotravelaboutandrootinthegroundfortheirownsubsistence，wouldtransmit，astrulyastheynowdotheirshortmuzzlesandlegs，andtheirtendencytofatten。Dray—horsesassuredlywouldnotlongtransmittheirgreatsizeandmassivelimbs，ifcompelledtoliveonacold，dampmountainousregion;wehaveindeedevidenceofsuchdeteriorationinthehorseswhichhaverunwildontheFalklandIslands。EuropeandogsinIndiaoftenfailtotransmittheirtruecharacter...完整阅读请扫描二维码下载丁香书院APP免费看：