Lastly, when organic beings are placed during several generations under conditions not natural to them, they are extremely liable to vary, which seems to be partly due to their reproductive systems having been specially affected, though in a lesser degree than when sterility ensues.
Azkenez, izaki organikoak zenbait mendez haientzat naturalak ez diren baldintzetan jartzen direnean, aldatzeko joera oso handia izaten dute, hau, dirudienez, aldez bederen, haien ugal-sistemak eragin berezia, nahiz eta antzutasuna gertatzen denean baino txikiagoa, jasaten duelako jazotzen delarik.