See Castle, W. E., Heredity, pp. 30-32, New York, 1911.

Doll, E. A., "Education and Inheritance," Journal of Education, Feb. 1, 1917.

Atwater's celebrated experiments proved that all the energy (food) which goes into an animal can be accounted for in the output of heat or work. They are conveniently summarized in Abderhalden's Text-book of Physiological Chemistry, p. 335.

In this connection see farther Raymond Pearl's review of Mr. Redfield's "Dynamic Evolution" (Journal of Heredity) VI, p. 254, and Paul Popenoe's review, "The Parents of Great Men," Journal of Heredity, VIII, pp. 400-408.

See Dr. Hrdlička's communication to the XIXth International Congress of Americanists, Dec. 28, 1915 (the proceedings were published at Washington, in March, 1917); or an account in the Journal of Heredity, VIII, pp. 98 ff., March, 1917.