The secretions of the genital canal and outlet in women are somewhat numerous. We have the odoriferous glands of sebaceous origin, and with them the prepuce of the clitoris which has been described as a kind of gigantic sebaceous follicle with the clitoris occupying its interior. (Hyrtl.) There is the secretion from the glands of Bartholin. There is again the vaginal secretion, opaque and albuminous, which appears to be alkaline when secreted, but becomes acid under the decomposing influence of bacteria, which are, however, harmless and not pathogenic. (Gow, _Obstetrical Society of London_, January 3, 1894.) There is, finally, the mucous uterine secretion, which is alkaline, and, being poured out during orgasm, is believed to protect the spermatozoa from destruction by the acid vaginal secretion. The belief that the mucus poured out in women during sexual excitement is feminine semen and therefore essential to conception had many remarkable consequences and was widespread until the seventeenth century. Thus, in the chapter "De Modo coeundi et de regimine eorum qui coeunt" of _De Secretis Mulierum_, there is insistence on the importance of the proper mixture of the male semen with the female semen and of arranging that it shall not escape from the vagina. The woman must lie quiet for several hours at least, not rising even to urinate, and when she gets up, be very temperate in eating and drinking, and not run or jump, pretending that she has a headache. It was the belief in feminine semen which led some theologians to lay down that a woman might masturbate if she had not experienced orgasm in coitus. Schurig in his _Muliebria_ (1729, pp. 159, et seq.) discusses the opinions of old authors regarding the nature, source, and uses of the female genital secretions, and quotes authorities against the old view that it was female semen. In a subsequent work (_Syllepsilogia_, 1731, pp. 3, et seq.) he returns to the same question, quotes authors who accept a feminine semen, shows that Harvey denied it any significance, and himself decides against it. It has not seriously been brought forward since. When erection is completed in both the man and the woman the conditions necessary for conjugation have at last been fulfilled. In all animals, even those most nearly allied to man, coitus is effected by the male approaching the female posteriorly. In man the normal method of male approach is anteriorly, face to face. Leonardo da Vinci, in a well-known drawing representing a sagittal section of a man and a woman connected in this position of so-called Venus obversa; has shown how well adapted the position is to the normal position of the organs in the human species.[105]