This slowness follows from all the inhabitants of the same country being already so well adapted to each other, that new places in the polity of nature do not occur until after long intervals, due to the occurrence of physical changes of some kind, or through the immigration of new forms.
Astiro aldatze hau herrialde bereko biztanle guztiak elkarren artean jada oso ongi moldaturik egotearen ondorio da; egon ere, hain ongi moldaturik egoten dira, non naturaren ekonomian ez den beste tokirik geratzen, harik eta aldi luzeak igaro ondoren nolabaiteko aldaketa fisikoen edo forma berrien inmigrazioaren ondorioz toki berriak agertu arte.