[59] "The Evolution Theory," II, p. 391.
[60] "Evolution and Adaptation," pp. 165 f.
[61] "Darwin and Modern Science," pp. 99, 101.
[62] "First Principles of Evolution," 1913, p. 224.
[63] "Darwiniana," p. 110.
[64] "Contributions to the Theory of Natural Selection," 1870.
[65] "The World of Life," 1911, pp. 340 f.
[66] A. Macalister, M. D., F. R. S., in Expositor, Vol. ix., 1910, p. 5.
[67] "The Fitness of the Environment," 1913, pp. 278 f.
[68] "The Fitness of the Environment," p. 312.