Prof. Alphonse de Candolle, son and successor of the great naturalist, wrote, a few years since, some interesting speculations on the probable future of the human race. This paper was deemed of sufficient value to be republished in the Annual Report of the Smithsonian Institution at Washington, for the year 1875. In the course of his discussion the eminent writer shows reason for believing that the last man is to be, not one man, but three. The future history of mankind, leaving out of the account any possible catastrophe that might suddenly extinguish the race, will be, in his view, somewhat as follows. For an extended period the population of the globe, favored by improved methods of agriculture, by migration to unoccupied lands, by general prevalence of peace consequent upon higher morality, will increase until the world is stocked with inhabitants to its fullest capacity. Then, after a period, will begin a process of depopulation. The conditions of life in the colder regions will be greatly changed by growing scarcity of the fuel supply; the world’s stock of minerals will be gradually exhausted by rust and wear, which will bring an end of ships, railroads and commerce, and thus increase the difficulty of maintaining life; and the incessant action of water, ice and air will constantly diminish the land area of the globe, until only mountains will remain as islands above the surface of the sea. Under the combined action of these agencies, the principles of natural selection and survival of the fittest will come into play with decisive effect, and in the struggle for life the weaker races will one by one succumb and disappear. Three races, however, exhibit qualities which fit them to survive beyond all others. 1. The white race, as represented by Europeans and their American descendants, thanks to their intelligence and habitual bravery, skill, and the confidence they can place in each other, will sustain the struggle. 2. The negroes also will prevail, on account of their physical vigor, power to resist malaria and to flourish in tropical regions, where the white race rapidly deteriorates. 3. The yellow race, represented principally by the Chinese, will maintain their place, since they have great vigor of stock, a capacity to exist on small resources, and alone seem sufficiently intelligent and robust to struggle in all latitudes with both the other races. The last man, then, is to be a white man, a negro and a Chinaman. But de Candolle seems to think that the negro may, after all, be the last man of this triumvirate. For the white man, occupying scattered islands in the colder regions, and deprived of fuel, might be exterminated by the more or less periodical invasions of ice from polar regions, while the black man could continue to subsist with little effort on the pulp of tropical melons.