Hyrtl, Op. cit., vol. ii, p. 39.
Sensations of pleasure without those of touch appear to be normal at the tip of the penis, as pointed out by Scripture, quoted in Alienist and Neurologist, January, 1898.
See the previous volume of these Studies, "Sexual Selection in Man," p. 161.
See, e.g., Ploss and Bartels, Das Weib, vol. i, beginning of chapter VI.