Not only the physical, but the mental development of man advances uniformly, and not _per saltum_. Physical qualities and defects may occur in a given number of negroes and Papuans, and may be absent in an equal number of Europeans, and conversely may occur in the one and be absent in the other; yet, in their mental condition, negroes and Papuans must always be regarded as in a lower order than Europeans. And if physical superiority is more widely diffused in European peoples than elsewhere, owing to higher culture, less exposure, and better nourishment, a more regular mode of life, and often also to the sexual selection prompted by æsthetic considerations, yet the reversion to such animal characteristics as do not exercise any modifying influence on the bodily development of the individual, occurs both in these and other races. I conclude these remarks with the reproduction of the fine passage with which Darwin ends his work on the descent of man. “Man may be excused for feeling some pride at having risen, though not through his own exertions, to the very summit of the organic scale; and the fact of his having thus risen, instead of having been aboriginally placed there, may give him hopes for a still higher destiny in the distant future. But we are not here concerned with hopes or fears, only with the truth, as far as our reason allows us to discover it. I have given the evidence to the best of my ability: and we must acknowledge, as it seems to me, that man, with all his noble qualities; with sympathy which feels for the most debased; with benevolence which extends not only to other men, but to the humblest living creature; with his god-like intellect, which has penetrated into the movements and constitution of the solar system;--with all these exalted powers, man still bears in his bodily frame the indelible stamp of his lowly origin.” APPENDIX. It was after I had finished this treatise that Mohnike’s _Blicke auf das Pflanzen- und Thierleben in den indischen Malaienländern_ (Münster, 1883) came into my hands. The author, who was for several years physician and medical superintendent in the Dutch Indies, has given an interesting account of the orang-utan. It appears that this animal is only found in the northern part of Sumatra, and is more common on the western than on the eastern coast. Even there the orang is only occasionally captured. The Dyaks of Borneo are fond of the flesh of this ape, which they shoot, especially in the interior of the island, with poisoned darts, projected from a blow-pipe. The wounded part is then carefully cut out. Mohnike states that in Borneo _Hylobates concolor_ is called Ouo-ouo by the Malays, and Kalawet by the Dyaks. Dark specimens of _Hylobates variegatus_ are in the Malay dialect called _itam_, or black Unko, and light specimens are called _puti_, or white Unko. A good illustration of _Hylobates leucogenys_ is given in the _Proceedings of the Zoological Society_, p. 680, Plate 42: London, 1877.