The determination of the exact meaning of a word that has only recently been proposed, and which has been explicitly defined by its author, is ordinarily an easy task; easier, that is, than in the case of an old term whose meaning has shifted through ages or through successive languages. Yet this youthful term, "eugenics," has already raced along a rapid and muddy course. Galton applied the word, in the first place, to the control of the racial evolution of the human species. Yet so far has the original meaning strayed that if one were to ask for definitions of eugenics from the passengers of a street car, one would get answers such as these: "the science of sex," "the control of venereal disease," "the causes and prevention of prostitution," "the science of health." Who has not heard laws to prevent the marriage of those venereally infected called eugenic? A school for sex education is called a school of eugenics. Even a milk and ice station has been similarly designated. At a recent important conference one speaker said, "As the hour is late, we must adjourn for lunch now, to be eugenic." Again, some workers for sexual hygiene explained that their movement had been greatly helped since they had labeled it eugenic. So it goes; a good word has been blurred and marred almost past recognition. There are several criteria for determining what is the best usage of any term. These are: (i) the formal definition by its originator, (2) its etymology, (3) reputable usage, and (4) fitness of limits. Just as facts fall into groups with natural limits, so words which have limits corresponding to these limits of the facts are to be preferred to words that are assigned arbitrary boundaries. In an article in Macmillan's Magazine, Vol. XII, pp. I57 and 3I8, in i865, entitled "Hereditary Talent and Character," we find