Ifanimalsandplantshadneverbeendomesticated，andwildonesalonehadbeenobserved，weshouldprobablyneverhaveheardthesaying，that\"likebegetslike。\"Thepropositionwouldhavebeenasself—evidentasthatallthebudsonthesametreearealike，thoughneitherpropositionisstrictlytrue。For，ashasoftenbeenremarked，probablynotwoindividualsareidenticallythesame。Allwildanimalsrecogniseeachother，whichshowsthatthereissomedifferencebetweenthem;andwhentheeyeiswellpractised，theshepherdknowseachsheep，andmancandistinguishafellow—
manoutofmillionsonmillionsofothermen。Someauthorshavegonesofarastomaintainthattheproductionofslightdifferencesisasmuchanecessaryfunctionofthepowersofgeneration，astheproductionofoffspringliketheirparents。Thisview，asweshallseeinafuturechapter，isnottheoreticallyprobable，thoughpracticallyitholdsgood。
Thesayingthat\"likebegetslike\"has，infact，arisenfromtheperfectconfidencefeltbybreeders，thatasuperiororinferioranimalwillgenerallyreproduceitskind;butthisverysuperiorityorinferiorityshowsthattheindividualinquestionhasdepartedslightlyfromitstype。
Thewholesubjectofinheritanceiswonderful。Whenanewcharacterarises，whateveritsnaturemaybe，itgenerallytendstobeinherited，atleastinatemporaryandsometimesinamostpersistentmanner。Whatcanbemorewonderfulthanthatsometriflingpeculiarity，notprimordiallyattachedtothespecies，shouldbetransmittedthroughthemaleorfemalesexualcells，whicharesominuteasnottobevisibletothenakedeye，andafterwardsthroughtheincessantchangesofalongcourseofdevelopment，undergoneeitherinthewomborintheegg，andultimatelyappearintheoffspringwhenmature，orevenwhenquiteold，asinthecaseofcertaindiseases？Oragain，whatcanbemorewonderfulthanthewell—ascertainedfactthattheminuteovuleofagoodmilkingcowwillproduceamale，fromwhomacell，inunionwithanovule，willproduceafemale，andshe，whenmature，willhavelargemammaryglands，yieldinganabundantsupplyofmilk，andevenmilkofaparticularquality？Nevertheless，therealsubjectofsurpriseis，asSirH。Hollandhaswellremarked（12/1。’MedicalNotesandReflections’3rdedition1855page267。）notthatacharactershouldbeinherited，butthatanyshouldeverfailtobeinherited。Inafuturechapter，devotedtoanhypothesiswhichIhavetermedpangenesis，anattemptwillbemadetoshowthemeansbywhichcharactersofallkindsaretransmittedfromgenerationtogeneration。
Somewriters（12/2。Mr。Buckleinhis’HistoryofCivilisation’expressesdoubtsonthesubject，owingtothewantofstatistics。SeealsoMr。Bowen，ProfessorofMoralPhilosophy，in’Proc。AmericanAcad。ofSciences’volume5page102。），whohavenotattendedtonaturalhistory，haveattemptedtoshowthattheforceofinheritancehasbeenmuchexaggerated。Thebreedersofanimalswouldsmileatsuchsimplicity;andiftheycondescendedtomakeanyanswer，mightaskwhatwouldbethechanceofwinningaprizeiftwoinferioranimalswerepairedtogether？Theymightaskwhetherthehalf—wildArabswereledbytheoreticalnotionstokeeppedigreesoftheirhorses？