Relevant facts are beginning to pour in from many directions; eugenic ideals are being given practical expression, and the science is rapidly gaining headway. It may be asked: "Well, what is it all about; are we as a nation not doing well--well enough?" Is it not true, as some have suggested, that this eugenic movement is but one more expression of England's temporary national hysteria transferred to this country? In answer to such queries let us state some of the conditions which have suggested to so many sober thinkers and observers that the time is arriving, has in fact arrived, when we must begin to think of the future of our communities and nations and of our race, rather than contentedly to read of and meditate upon the great achievements of our past, or to parade with self-satisfied air through our glass houses of Anglo-Saxon supremacy. Even were we unthreatened, were we amply holding our own, the mere fact of the possibility of a natural increase of human capacity would make it a practical subject of the utmost importance. We may be sure that somewhere a nation will avail itself of such a possibility as the increase of inherent native talent, physical, mental, moral, and will tend to become a strong and dominant people. Why should not _we_ be that people? It seems that the facts that lead us to think of the future in this matter are of two quite distinct classes. First, we have a great mass of data relative to the composition of our societies and to the changing character of our population, social data of deep significance when broadly viewed and thoughtfully considered. Second, there are certain biological considerations, which all apart from existing social conditions should warn us to be on the lookout. First let us review briefly some of the latter, some of those biological considerations which lead us to regard thoughtfully the problem of the future evolution of man and his societies.