Riolan (_Anthropographia_, 1626, p. 294) referred to the constriction and dilation of the vulva under the influence of sexual excitement. It is said that in Abyssinia women can, when adopting the straddling posture of coitus, by the movements of their own vaginal muscles alone, grasp the male organ and cause ejaculation, although the man remains passive. According to Lorion the Annamites, adopting the normal posture of coitus, introduce the penis when flaccid or only half erect, the contraction of the vaginal walls completing the process; the penis is very small in this people. It is recognized by gynæcologists that the condition of vaginismus, in which there is spasmodic contraction of the vagina, making intercourse painful or impossible, is but a morbid exaggeration of the normal contraction which occurs in sexual excitement. Even in the absence of sexual excitement there is a vague affection, occurring in both married and unmarried women, and not, it would seem, necessarily hysterical, characterized by quivering or twitching of the vulva; I am told that this is popularly termed "flackering of the shape" in Yorkshire and "taittering of the lips" in Ireland. It may be added that quivering of the gluteal muscles also takes place during detumescence, and that in Indian medicine this is likewise regarded as a sign of sexual desire in women, apart from coitus. A non-medical correspondent in Australia, W.J. Chidley, from whom I have received many communications on this subject, is strongly of opinion from his own observations that not only does the uterus take an active part in coitus, but that under natural conditions the vagina also plays an active part in the process. He was led to suspect such an action many years ago, as well by an experience of his own, as also by hearing from a young woman who met her lover after a long absence that by the excitement thus aroused a tape attached to the underclothes had been drawn into the vagina. Since then the confidences of various friends, together with observations of animals, have confirmed him in the view that the general belief that coitus must be effected by forcible entry of the male organ into a passive vagina is incorrect. He considers that under normal circumstances coitus should take place but rarely, and then only under the most favorable circumstances, perhaps exclusively in spring, and, most especially, only when the woman is ready for it. Then, when in the arms of the man she loves, the vagina, in sympathy with the active movements of the womb, becomes distended at the touch of the turgescent, but not fully erect, penis, "flashes open and draws in the male organ." "All animals," he adds, "have sexual intercourse by the male organ being _drawn_, not forced, into the female.