The whole tendency of recent science, however, has been adverse to the doctrine of separate centres of creation, even in the case of animal and vegetable life. In temperate North America there are two hundred and seven species of quadrupeds, of which only eight, and these polar animals, are found in the north of Europe or Asia. If North America be an instance of a separate centre of creation for its peculiar species, why should God create the same species of man in eight different localities? This would make man an exception in creation. There is, moreover, no need of creating man in many separate localities; for, unlike the polar bears and the Norwegian firs, which cannot live at the equator, man can adapt himself to the most varied climates and conditions. For replies to Agassiz, see Bib. Sac., 19:607-632; Princeton Rev., 1862:435-464. (_b_) It is objected, moreover, that the diversities of size, color, and physical conformation, among the various families of mankind, are inconsistent with the theory of a common origin. But we reply that these diversities are of a superficial character, and can be accounted for by corresponding diversities of condition and environment. Changes which have been observed and recorded within historic times show that the differences alluded to may be the result of slowly accumulated divergences from one and the same original and ancestral type. The difficulty in the case, moreover, is greatly relieved when we remember (1) that the period during which these divergences have arisen is by no means limited to six thousand years (see note on the antiquity of the race, pages 224-226); and (2) that, since species in general exhibit their greatest power of divergence into varieties immediately after their first introduction, all the varieties of the human species may have presented themselves in man’s earliest history.