When, on the one hand, we see domesticated animals and plants, though often weak and sickly, breeding freely under confinement; and when, on the other hand, we see individuals, though taken young from a state of nature perfectly tamed, long-lived, and healthy (of which I could give numerous instances), yet having their reproductive system so seriously affected by unperceived causes as to fail to act, we need not be surprised at this system, when it does act under confinement, acting irregularly, and producing offspring somewhat unlike their parents.
Ikusten ditugunean, alde batetik, etxekoturiko landare eta animaliak, ahul eta gaixotiak maiz, hesipeko egoeran mugapenik gabe umatzen, eta bestetik, ikusten dugunean, ongi heziriko banakoek, natur egoeratik gazterik atereak izan arren, luzaro eta osasuntsu bizi ondoren-honetaz hain-bat exenplu eman nezakeelarik-, hala ere, ugal-aparatua ez funtzionatzeraino hondaturik dutela, zerk eraginik ez dakigularik, ez gaitu harritu behar aparatu honek, hesipeko egoeran funtzionatzen duenean, irregularki egiteak eta gurasoen ezberdin samarrak diren ondorengoak izatea.