It is certainly true that climate tends to produce these effects by its direct action on individuals. Anyone who has lived for a time in the southern climes must have noted these effects upon himself. But we have no proof that the effects of climate are directly inherited. It suffices to suppose that the direct effects are imposed afresh by the climate on the minds of each generation. This view is borne out by the fact that two races may live for many generations in the same climate and yet remain very different in temperament in these respects; for example the Irish climate is very similar to the English, perhaps even more misty and damp; yet the Irish have much more wit and liveliness than the English. And in every case in which adaptation to physical environment has clearly become innate or racial, an explanation can be suggested in terms of selection of spontaneous variations, or of crossing of races. Thus, the approximation of the American people to the type of the aboriginals, if it is actual, and some observers deny it, may well be due to the small infusion of the native blood which has admittedly taken place. It may well be that certain qualities of the Red Indian, for example, the straight dark hair and prominent cheek bones, are what the biologists call ‘dominant characters’ when the Indian is crossed with the European; that is, qualities which always assert themselves in the offspring, to the exclusion of the corresponding quality of the other race involved in the cross. If that is so, a very small proportion of Indian blood would suffice to make these features very common throughout the population of America. As an exception to the supposed law of direct hereditary adaptation to climate take the colour of the skin. The black negroes live in the hot moist regions of Africa, and it has been said that pigmentation is the hereditary effect of a hot moist climate. But there are men of a different race who have long lived in an equally hot and moist climate, but who do not show this effect—namely, tribes in the heart of Borneo, right under the equator, whose skins are hardly darker than the average English skins and less dark than the Southern Europeans’. Take again the indolence of the peoples of warm hot climates and the energy of peoples of colder climates. These certainly seem to be racial qualities; but their distribution is adequately explained by the indirect effect of physical environment exerted by way of natural selection; and these differences of energy afford the best illustration of such indirect action of physical environment in determining racial mental qualities.