The consideration of these facts on dimorphism, as well as of the results of reciprocal crosses, clearly leads to the conclusion that the primary cause of the sterility of crossed species is confined to differences in their sexual elements.
Landare dimorfiko eta trimorfikoen eta haien ondorengo ezlegezkoen batze ezlegezkoen antzutasunari buruz aipaturiko egitateek gertagarri bihurtzen dute agian lokarri ezezagunen bat izatea, kasu guztietan lehen batzeen ugalkortasun maila ondorengoenarekin lotzen duena.