Ontheotherhand，withmaleanimals，itisnotoriousthatthesecondarysexualcharactersaremoreorlesscompletelylostwhentheyaresubjectedtocastration。Thus，iftheoperationbeperformedonayoungcock，henever，asYarrellstates，crowsagain;thecomb，wattles，andspursdonotgrowtotheirfullsize，andthehacklesassumeanintermediateappearancebetweentruehacklesandthefeathersofthehen。Casesarerecordedofconfinement，whichoftenaffectsthereproductivesystem，causinganalogousresults。Butcharactersproperlyconfinedtothefemalearelikewiseacquiredbythemale;
thecapontakestosittingoneggs，andwillbringupchickens;andwhatismorecurious，theutterlysterilemalehybridsfromthepheasantandthefowlactinthesamemanner，\"theirdelightbeingtowatchwhenthehensleavetheirnests，andtotakeonthemselvestheofficeofasitter。\"（13/57。
’CottageGardener’1860page379。）ThatadmirableobserverReaumur（13/58。
’ArtdefaireEclore’etc。1749tome2page8。）assertsthatacock，bybeinglongconfinedinsolitudeanddarkness，canbetaughttotakechargeofyoungchickens;hethenuttersapeculiarcry，andretainsduringhiswholelifethisnewlyacquiredmaternalinstinct。Themanywell—ascertainedcasesofvariousmalemammalsgivingmilkshowsthattheirrudimentarymammaryglandsretainthiscapacityinalatentcondition。
Wethusseethatinmany，probablyinallcases，thesecondarycharactersofeachsexliedormantorlatentintheoppositesex，readytobeevolvedunderpeculiarcircumstances。Wecanthusunderstandhow，forinstance，itispossibleforagoodmilkingcowtotransmithergoodqualitiesthroughhermaleoffspringtofuturegenerations;forwemayconfidentlybelievethatthesequalitiesarepresent，thoughlatent，inthemalesofeachgeneration。