If the existence of the same species at distant and isolated points of the earth's surface can in many instances be explained on the view of each species having migrated from a single birthplace; then, considering our ignorance with respect to former climatical and geographical changes, and to the various occasional means of transport, the belief that a single birthplace is the law seems to me incomparably the safest.
Baldin, epezie bakoitza sorleku bakarretik migratu delako eritziaren barruan, kasu askotan Lurraren azaleraren puntu urrun eta isolatuetan espezie bera izatea azaltzerik badago, orduan, kontuan harturik antzinako klima-aldaketez eta noizbehinka izan zitezkeen garraiabideez dugun ezjakintasuna, araua sorleku bakarra dela uste izateari deritzot konparaziorik gabe seguruena.