The most notable steps in this direction have been taken in Germany. For an account of the experiment at Karlsruhe, see Die Neue Generation, Dec., 1908.
Wiethknudsen (as quoted in Sexual-Probleme, Dec., 1908, p. 837) speaks strongly, but not too strongly, concerning the folly of any indiscriminate endowment of procreation.
On the scientific side, in addition to the fruitful methods of statistical biometrics, which have already been mentioned, much promise attaches to work along the lines initiated by Mendel; see W. Bateson, Mendel's Principles of Heredity, 1909; also, W. H. Lock, Recent Progress in the Study of Variation, Heredity, and Evolution, and R. C. Punnett, Mendelism, 1907 (American edition, with interesting preface by Gaylord Wilshire, from the Socialistic point of view, 1909).
The study of the right conditions for procreation is very ancient. In modern times we find that even the very first French medical book in the vulgar tongue, the Régime du Corps, written by Alebrand of Florence (who was physician to the King of France), in 1256, is largely devoted to this matter, concerning which it gives much sound advice. See J. B. Soalhat, Les Idées de Maistre Alebrand de Florence sur la Puériculture, Thèse de Paris, 1908.