[179] Kornhauser, A. W., "Economic Standing of Parents and the Intelligence of their Children," _Jour. of Educ. Psychology_, Vol. IX., pp. 159-164, March, 1918. [180] The coefficient of contingency is similar in significance to the coefficient of correlation, with which readers have already become familiar. Miss Perrin's study is in _Biometrika_, III (1904), pp. 467-469. [181] "The Social Waste of Unguided Personal Ability." By Erville B. Woods, _American Journal of Sociology_, XIX (1913), pp. 358-369. [182] See also "Eugenics: With Special Reference to Intellect and Character," by E. L. Thorndike. In _Eugenics: Twelve University Lectures_, pp. 319-342, New York, 1914. [183] See U. S. Department of Labor, Children's Bureau Publication, No. 7, "Laws Relating to Mothers' Pensions in the United States, Denmark and New Zealand," Washington, 1914. [184] _American Journal of Sociology_, Vol. XX, No. 1, pp. 96-103, July, 1914. [185] According to Captain (now Lt. Col.) E. B. Vedder of the Medical Corps, U. S. A., 50% of the Negroes of the class applying for enlistment in the army are syphilitic. He believes that the amount of infection among Negro women is about the same. (_Therapeutic Gazette_, May 15, 1916.) Venereal disease must, then, play a much more important part than is generally supposed, in cutting down the birth-rate of the Negro race, but it would of course be a mistake to suppose that an abnormally low birth-rate among Negroes is always to be explained on this ground. Professor Kelly Miller points out (_Scientific Monthly_, June, 1917) that the birth-rate among college professors at Howard University, the leading Negro institution for higher education, is only 0.7 of a child and that the completed families will hardly have more than two children. He attributes this to (1) the long period of education required of Negro "intellectuals", (2) the high standard of living required of them, and (3) the unwillingness of some of them to bring children into the world, because of the feeling that these children would suffer from race prejudice. [186] One can not draw a hard and fast distinction between reason and instinct in this way, nor deny to animals all ability to reason. We have simplified the case to make it more graphic. The fact that higher animals may have mental processes corresponding to some of those we call reason in man does not impair the validity of our generalization, for the present purpose. [187] See _Jewish Eugenics and Other Essays_, By Rabbi Max Reichler, New York, Bloch Publishing Co., 1916. [188] Dublin, Louis I., "Significance of the Declining Birth Rate," _Congressional Record_, Jan. 11, 1918. [189] At the request of Alexander Graham Bell, founder and director of the Genealogical Record Office, Paul Popenoe made an examination and report on these records in the fall of 1916. Thanks are due to Dr. Bell for permitting the use in this chapter of two portions of the investigation.