Whenever it is fully admitted, as it will some day be, that each species has proceeded from a single birthplace, and when in the course of time we know something definite about the means of distribution, we shall be enabled to speculate with security on the former extension of the land.
Espezie bakoitza sorleku bakarretik etorria dela erabat onartzen denean, noizbait onartuko den moduan, eta, urteak joan urteak etorri, sakabanatzeko bitartekoei buruz zerbait zehatzik jakiten dugunean, segurtasunez pentsatu ahal izanen dugu antzina lehorrak zuen hedaduraz.