[34] The more carefully animals are observed, the more often this is found to be the case, even with respect to species which possess no obvious and elaborate process for obtaining tumescence. See, for instance, the detailed and very instructive account--too long to quote here--given by E. Selous of the preliminaries to intercourse practised by a pair of great crested grebes, while nest-building. Intercourse only took place with much difficulty, after many fruitless invitations, more usually given by the female. ("Observational Diary of the Habits of the Great Crested Grebe," _Zöologist_, September, 1901.) It is exactly the same with savages. The observation of Foley (_Bulletin de la Société d'Anthropologie de Paris_, November 6, 1879) that in savages "sexual erethism is very difficult" is of great significance and certainly in accordance with the facts. This difficulty of erethism is the real cause of many savage practices which to the civilized person often seem perverse; the women of the Caroline Islands, for instance, as described by Finsch, require the tongue or even the teeth to be applied to the clitoris, or a great ant to be applied to bite the parts, in order to stimulate orgasm. Westermarck, after quoting a remark of Mariner's concerning the women of Tonga,--"it must not be supposed that these women are always easily won; the greatest attentions and the most fervent solicitations are sometimes requisite, even though there be no other lover in the way,"--adds that these words "hold true for a great many, not to say all, savage and barbarous races now existing." (_Human Marriage_, p. 163.) The old notions, however, as to the sexual licentiousness of peoples living in natural conditions have scarcely yet disappeared. See Appendix A; "The Sexual Instinct in Savages." [35] In men a certain degree of tumescence is essential before coitus can be effected at all; in women, though tumescence is not essential to coitus, it is essential to orgasm and the accompanying physical and psychic relief. The preference which women often experience for prolonged coitus is not, as might possibly be imagined, due to sensuality, but has a profound physiological basis. [36] Stanley Hall, _Adolescence_, vol. i, p. 223. [37] See Lagrange's _Physiology of Bodily Exercise_, especially chapter ii. It is a significant fact that, as Sergi remarks (_Les Emotions_, p. 330), the physiological results of dancing are identical with the physiological results of pleasure. [38] Groos, _Spiele der Menschen_, p. 112. Zmigrodzki (_Die Mutter bei den Volkern des Arischen Stammes_, p. 414 et seq.) has an interesting passage describing the dance--especially the Russian dance--in its orgiastic aspects. [39] Féré, "L'Influence sur le Travail Volontaire d'un muscle de l'activité d'autres muscles," _Nouvelles Iconographie de la Salpêtrière_, 1901.