Sidis, Boris, M.A., Ph.D., M.D., "Neurosis and Eugenics," Medical Review of Reviews, Vol. XXI, No. 10, pp. 587-594, New York, October, 1915. A psychologist who writes of "some miraculous germ-plasm (chromatin) with wonderful dominant 'units' (Chromosomes)" is hardly a competent critic of the facts of heredity.

In a letter to the Journal of Heredity, under date of August 4, 1916.

Galton, Francis, Inquiries into Human Faculty, p. 167, London, 1907.

Woods, Frederick Adams, Heredity in Royalty, New York, 1906.

Op. cit., pp. 170-171.

Thorndike, E. L., "Measurements of Twins," Arch. of Philos., Psych. and Sci. Methods, No. 1, New York, 1905; summarized in his Educational Psychology, Vol. III, pp. 247-251, New York, 1914. Measured on a scale where 1 = identity, he found that twins showed a resemblance to each other of about .75, while ordinary brothers of about the same age resembled each other to the extent of about .50 only. The resemblance was approximately the same in both physical and mental traits.