The fact, as we have seen, that all past and present organic beings can be arranged within a few great classes, in groups subordinate to groups, and with the extinct groups often falling in between the recent groups, is intelligible on the theory of natural selection with its contingencies of extinction and divergence of character.
Ikusi dugun moduan, lehengo eta oraingo izaki organiko guztiak klase handi gutxi batzuen barruan ordenatu ahal izatea, bata bestearen menpeko taldeetan, talde iraungiak maiz oraintsuko taldeen bitarteko lekuetan direlarik, ulergarria da hautespen naturalaren teoriaren barruan, beronen arabera gertatzen den iraungipen eta ezaugarri dibergentzia eta guzti.