The law of the fertility of “crosses” as applied to civilisation or “social efficiency” alike on the physical and psychical plane requires, as a condition of effective operation, internationalism. It is of course true that throughout history the “crossing” of national types has been largely achieved by means of war, conquest, and subjugation. But this, though subserving progress in the long run, has been a most wasteful, indirect, and unsafe method, the selection being determined by no clear view of the future or of any higher purpose of social efficiency. Just in proportion as internationalism promotes free intercourse between nations for higher purposes of peaceful interest, will blending of races by intermarriage be determined on grounds of affinity more fruitful of improved racial efficiency, and new modifications of species more numerous and more novel will compete with one another as factors in the civilisation of the world, raising the character and intensity of the competition and enhancing the pace of human progress.
Nay, we may carry the biological analogy still farther, following the insistence of Professor Pearson regarding the necessity of bringing direct social pressure, of public opinion or of law, to prevent the fatal process of breeding from “bad stock.” If the ordinary processes of physical degeneracy within the nation do not