[50] The Cell in Development and Inheritance, pp. 413 et seq. New York, 1906.

[51] The Duration of Life.

[52] Zeitschrift f. Biologie, 1893, bd. 30, p. 73.

[53] Heredity and Environment.

[54] Journal of the American Medical Association, vol. lix, n. 7, p. 523.

[55] I, q. 76, corp.

[56] Ia, q. 118, a. 2, ad 2.

[57] U. d. Entstchungsweise der vordern Verdoppelung. Deutsch. Archiv. f. klin. Med., 1887.

[58a] U. d. Furchung des Eies bei Doppelbildungen. Breslauer Aertzliche Zeitschrift, 1887.

[58b] Chap. vi, p. 69. New York, 1906.