[92] W. Heape, "The Menstruation of Semnopithecus Entellus," Philosophical Transactions, 1894; "Menstruation and Ovulation of Macacus Rhesus," Philosophical Transactions, 1897.
[93] W. L. Distant, "Notes on the Chacma Baboon," Zoölogist, January, 1897, p, 29.
[94] Nature, March 23, 1899.
[95] W. Heape, "The Menstruation of Semnopithecus Entellus," Philosophical Transactions, 1894, p. 483; Bland Sutton, Surgical Diseases of the Ovaries, 1896.
[96] T. Bryce and J. Teacher (Contributions to the Study of the Early Development of the Human Ovum, 1908), putting the matter somewhat differently, regard menstruation as a cyclical process, providing for the maintenance of the endometrium in a suitable condition of immaturity for the production of the decidua of pregnancy, which they believe may take place at any time of the month, though most favorably shortly before or after a menstrual period which has been accompanied by ovulation.
[97] Robinson, American Gynecological and Obstetrical Journal, August, 1905.
[98] Bossi, Annali di Ostetrica e Ginecologia, September, 1896; summarized in the British Medical Journal, October 31, 1896. As regards the more normal influence of the ovaries over the uterus, see e.g. Carmichael and F. H. A. Marshall, "Correlation of the Ovarian and Uterine Functions," Proceedings Royal Society, vol. 79, Series B, 1907.
[99] Beuttner, Centralblatt für Gynäkologie, No. 49, 1893; summarized in British Medical Journal, December, 1893. Many cases show that pregnancy may occur in the absence of menstruation. See, e.g., Nouvelles Archives d'Obstétrique et de Gynécologie, 25 Janvier, 1894, supplement, p. 9.
[100] It is still possible, and even probable, that the primordial cause of both phenomena is the same. Heape (Transactions Obstetrical Society of London, 1898, vol. xl, p. 161) argues that both menstruation and ovulation are closely connected with and influenced by congestion, and that in the primitive condition they are largely due to the same cause. This primary cause he is inclined to regard as a ferment, due to a change in the constitution of the blood brought about by climatic influences and food, which he proposes to call gonadin. (W. Heape, Proceedings of Royal Society, 1905, vol. B. 76, p. 266.) Marshall, who has found that in the ferret and other animals, ovulation may be dependent upon copulation, also considers that ovulation and menstruation, though connected and able to react on each other, may both be dependent upon a common cause; he finds that in bitches and rats heat can be produced by injection of extract from ovaries in the œstrous state (F. H. A. Marshall, Philosophical Transactions, 1903, vol. B. 196; also Marshall and Jolly, id., 1905, B. 198). Cf. C. J. Bond, "An Inquiry Into Some Points in Uterine and Ovarian Physiology and Pathology in Rabbits," British Medical Journal, July 21, 1906.
[101] Pouchet, Théorie de l'Ovulation Spontanée, 1847. As Blair Bell and Pontland Hick remark ("Menstruation," British Medical Journal, March 6, 1909), the repeated œstrus of unimpregnated animals (once a fortnight in rabbits) is surely comparable to menstruation.
[102] Tait, Provincial Medical Journal, May, 1891; J. Beard, The Span of Gestation, 1897, p. 69. Lawson Tait is reduced to the assertion that ovulation and menstruation are identical.
[103] As Moll points out, even the secondary sexual characters have undergone a somewhat similar change. The beard was once an important sexual attraction, but men can now afford to dispense with it without fear of loss in attractiveness. (Libido Sexualis, Band I, p. 387.) These points are discussed at greater length in the fourth volume of these Studies, "Sexual Selection in Man."
[104] It is not absolutely established that in menstruating animals the period of menstruation is always a period of sexual congress; probably not, the influence of menstruation being diminished by the more fundamental influence of breeding seasons, which affect the male also; monkeys have a breeding season, though they menstruate regularly all the year round.
[105] See Appendix A.
[106] Bland Sutton, loc. cit., p. 896.
[107] See H. Ellis, Man and Woman, Chapter XI.
[108] This is by no means true of European women only. Thus, we read in an Arabic book, The Perfumed Garden, that women have an aversion to coitus during menstruation. On the other hand, the old Hindoo physician, Susruta, appears to have stated that a tendency to run after men is one of the signs of menstruation.
[109] The actual period of the menstrual flow corresponds, in Heape's terminology, to the congestive stage, or pro-œstrum, in female animals; the œstrus, or period of sexual desire, immediately follows the pro-œstrum, and is the direct result of it. See Heape, "The 'Sexual Season' of Mammals," Quarterly Journal of Microscopical Science, 1900, vol. xliv, Part I.
[110] It may be noted that (as Barnes, Oliver, and others have pointed out) there is heightened blood-pressure during menstruation. Haig remarks that he has found a tendency for high pressure to be accompanied by increased sexual appetite (Uric Acid, 6th edition, p. 155).
[111] Sir W. F. Wade, however, remarked, some years ago, in his Ingleby Lectures (Lancet, June 5, 1886): "It is far from exceptional to find that there is an extreme enhancement of concupiscence in the immediate precatamenial period," and adds, "I am satisfied that evidence is obtainable that in some instances, ardor is at its maximum during the actual period, and suspect that cases occur in which it is almost, if not entirely, limited to that time." Long ago, however, the genius of Haller had noted the same fact. More recently, Icard (La Femme, Chapter VI and elsewhere, e.g., p. 125) has brought forward much evidence in confirmation of this view. It may be added that there is considerable significance in the fact that the erotic hallucinations, which are not infrequently experienced by women under the influence of nitrous oxide gas, are more likely to appear at the monthly period than at any other time. (D. W. Buxton, Anesthetics, 1892, p. 61.)
[112] Gehrung considers that in healthy young girls amorous sensations are normal