Let us now see whether the several facts and laws relating to the geological succession of organic beings accord best with the common view of the immutability of species, or with that of their slow and gradual modification, through variation and natural selection.
Dakusagun orain izaki organikoen hurrenketa geologikoari dagozkion egitate ezberdinak zerekin datozen batago, espezien aldaezintasunari defendatzen duen eritzi arruntarekin, ala aldakuntza eta hautespenaren bidez gauzaturiko haien astiroko eta mailaz mailako eraldaketari eusten dionarekin.