[1] See Darwin: Expression of Emotions in Man and Animals, New York, 1905, pp. 101, 117.
[2] Spencer: Principles of Psychology, London, 1855.
[3] McDougall: Introduction to Social Psychology, London, 1908, pp. 49, 59.
[4] Crile: Boston Medical and Surgical Journal, 1910, clxiii, p. 893.
[5] Macleod: Diabetes, etc., p. 80.
[6] Darwin: Loc. cit., p. 72.
[7] Nasse: Archiv für die gesammte Physiologie, 1869, ii, p. 106; 1877, xiv, p. 483.
[8] Frentzel: Archiv für die gesammte Physiologie, 1894, lvi, p. 280.
[9] Zuntz: Oppenheimer’s Handbuch der Biochemie, Jena, 1911, iv (first half), p. 841.
[10] Benedict and Cathcart: Muscular Work, a Metabolic Study, Washington, 1913, pp. 85–87.