Nevertheless, the naturalist, in travelling, for instance, from north to south, never fails to be struck by the manner in which successive groups of beings, specifically distinct, though nearly related, replace each other.
Hala ere, naturalistari, iparretik hegorantz bidaiatzean, hutsik gabe pizten dio arreta, hurrenez hurreneko izaki talde espezifikoki ezberdinek, nahiz eta hurbilek, elkar nola ordezkatzen duten ikusteak.