but this is scarcely ever possible, and we are forced to look to other species and genera of the same group, that is to the collateral descendants from the same parent-form, in order to see what gradations are possible, and for the chance of some gradations having been transmitted in an unaltered or little altered condition.
baina ia sekula ere ez dago hau egiterik, eta beharturik aurkitu ohi gara talde bereko beste espezie eta genero batzuk, hau da, guraso-forma beraren ondorengo kolateralak, kontuan hartzera, ea zeintzuk mailaketa aurkitu ahal diren eta mailaketa batzuk aldagabe edo gutxi aldaturik transmititu diren ikusteko.