Two things are necessary for the continued existence of a race: it must remain itself, and it must breed its best. Every race is the result of ages of development which evolves specialized capacities that make the race what it is and render it capable of creative achievement. These specialized capacities (which particularly mark the superior races), being relatively recent developments, are highly unstable. They are what biologists call "recessive" characters; that is, they are not nearly so "dominant" as the older, generalized characters which races inherit from remote ages and which have therefore been more firmly stamped upon the germ-plasm. Hence, when a highly specialized stock interbreeds with a different stock, the newer, less stable, specialized characters are bred out, the variation, no matter how great its potential value to human evolution, being _irretrievably lost_. This occurs even in the mating of two superior stocks if these stocks are widely dissimilar in character. The valuable specializations of both breeds cancel out, and the mixed offspring tend strongly to revert to generalized mediocrity. And, of course, the more primitive a type is, the more prepotent it is. This is why crossings with the negro are uniformly fatal. Whites, Amerindians, or Asiatics--all are alike vanquished by the invincible prepotency of the more primitive, generalized, and lower negro blood. There is no immediate danger of the world being swamped by black blood. But there is a very imminent danger that the white stocks may be swamped by Asiatic blood. The white man's very triumphs have evoked this danger. His virtual abolition of distance has destroyed the protection which nature once conferred. Formerly mankind dwelt in such dispersed isolation that wholesale contact of distant, diverse stocks was practically impossible. But with the development of cheap and rapid transportation, nature's barriers are down. Unless man erects and maintains artificial barriers the various races will increasingly mingle, and the inevitable result will be the supplanting or absorption of the higher by the lower types. We can see this process working out in almost every phase of modern migration. The white immigration into Latin America is the exception which proves the rule. That particular migration is, of course, beneficent, since it means the influx of relatively high types into undeveloped lands, sparsely populated by types either no higher or much lower than the new arrivals. But almost everywhere else, whether we consider interwhite migrations or colored encroachments on white lands, the net result is an expansion of lower and a contraction of higher stocks, the process being thus a disgenic one. Even in Asia the evils of modern migration are beginning to show. The Japanese Government has been obliged to prohibit the influx of Chinese and Korean coolies who were undercutting Japanese labor and thus undermining the economic bases of Japanese life.