[79] The Human Body, p. 92.
[80] Op. cit., p. 73
[81] Schäfer’s Text-Book of Physiology.
[82] Manual of Human Physiology. Leonard Hill, p. 369.
[83] Op. cit., p. 371.
[84] Text Book of Embryology. Vertebrata with the exception of Mammalia. Vol. II., 1919, p. 106.
[85] Physiological Psychology. W. McDougall, p. 156 (1911).
[86] Prehistoric Man and His Story, p. 92.
[87] Schafer, p. 922.
[88] Op. cit. p. 21.