Galton formulated a general law of inheritance which declared that an individual receives one-half of his inheritance from his two parents, one-fourth from his four grandparents, one-eighth from his great-grandparents, one-sixteenth from his great-great grandparents, and so on by diminishing fractions to his primordial ancestors, the sum of all these fractions added together contributing to the whole of the inherited make-up. The trouble with this generalization, from the modern Mendelian point of view, is that it fails to define what "characters" one would get in the one-half that came from one's parents, or the one-fourth from one's grandparents. The whole of our inheritance is not composed of these indefinitely made up fractional parts. We are interested rather in those more specific traits or characters, mental or physical, which, in the Mendelian view, are structural and functional units, making up a mosaic rather than a blend. The laws of heredity are concerned with the precise behavior, during a series of generations, of these specific unit characters. This behavior, as the study of Genetics shows, may be determined in lesser organisms by experiment. Once determined, they are subject to prophecy. The problem of human heredity is now seen to be infinitely more complex than imagined by Galton and his followers, and the optimistic hope of elevating Eugenics to the level of a religion is a futile one. Most of the Eugenists, including Professor Karl Pearson and his colleagues of the Eugenics Laboratory of the University of London and of the biometric laboratory in University College, have retained the age-old point of view of "Nature vs. Nurture" and have attempted to show the predominating influence of Heredity AS OPPOSED TO Environment. This may be true; but demonstrated and repeated in investigation after investigation, it nevertheless remains fruitless and unprofitable from the practical point of view. We should not minimize the great outstanding service of Eugenics for critical and diagnostic investigations. It demonstrates, not in terms of glittering generalization but in statistical studies of investigations reduced to measurement and number, that uncontrolled fertility is universally correlated with disease, poverty, overcrowding and the transmission of hereditable taints. Professor Pearson and his associates show us that "if fertility be correlated with anti-social hereditary characters, a population will inevitably degenerate."