[Furtherthesamepassageservesforurineandsemen；andwhateveranimalshavebothkindsofexcrement，thatofliquidandthatofsolidnutriment，dischargethesemenbythesamepassageastheliquidexcrement（foritisasecretionofaliquid，sincethenutrimentofallanimalsisratherliquidthansolid），butthosewhichhavenoliquidexcrementdischargeitatthepassageofthesolidresidua。Moreover，waste—productsarealwaysmorbid，buttheremovalofthesecretionisuseful；nowthedischargeofthesemenparticipatesinbothcharacteristicsbecauseittakesupsomeofthenon—usefulnutriment。Butifitwereawaste—productitwouldbealwaysharmful；asitis，itisnotso。]
Fromwhathasbeensaid，itisclearthatsemenisasecretionofusefulnutriment，andthatinitslaststage，whetheritisproducedbyallorno。
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Afterthiswemustdistinguishofwhatsortofnutrimentitisasecretion，andmustdiscussthecatameniawhichoccurincertainofthevivipara。Forthusweshallmakeitclear（1）whetherthefemalealsoproducessemenlikethemaleandthefoetusisasinglemixtureoftwosemens，orwhethernosemenissecretedbythefemale，and，（2）
ifnot，whethershecontributesnothingelseeithertogenerationbutonlyprovidesareceptacle，orwhethershedoescontributesomething，and，ifso，howandinwhatmannershedoesso。