_Edis_ recommends that in cases in which there is sterility dependent upon backward displacements of the uterus, that the organ should be replaced while the patient is in the genu-pectoral posture, and a pessary inserted; coitus should then be effected without the patient’s changing her posture. In the human species as compared with the lower animals, there has been a notable diminution in the frequency of the separate acts of intercourse, a diminution dependent upon the higher vital aims of the former. _Burdach_ formulates as a physiological law that the frequency of sexual intercourse is inversely related to the duration of the act. Amongst all civilized races, sexual intercourse ceases during menstruation, since in the normal man there is aversion to intercourse with a menstruating female. By the Mosaic law, intercourse with a woman during menstruation and for seven days after the cessation of the flow, was forbidden under pain of death. The _Talmud_ further ordains that a purifying bath shall be taken by the woman a week after menstruation. By intercourse itself, moreover, both man and woman were rendered unclean to the evening; and, according to the Mosaic law, both must bathe after the act of coitus. In the _Koran_, also, intercourse is forbidden during menstruation, and until the woman has been purified with water. The law’s of Islam demand from a man who marries a virgin that he shall have intercourse with her the first seven nights in succession; whilst he who marries a wife no longer virgin, needs to visit her only the first three nights in succession. Subsequently, during married life, the Mohammedan shall have intercourse with his wife regularly once a week. Amongst many savage races, intercourse is forbidden with a woman during pregnancy, the puerperium, and lactation. The first act of intercourse is difficult and painful to the virgin. At times the rupture of the hymen is exceedingly difficult. Even after this, it is some time before genuine pleasure is experienced in sexual intercourse. To the female, intercourse is harmful when performed with undue frequency, or during menstruation, or indiscriminately throughout pregnancy, or during the puerperium, or incompletely or in an unnatural manner, or finally when performed in an unsuitable bodily attitude. “Unduly frequent performance of the act of coitus,” writes _Hegar_, “which is liable to occur either in marital or in illicit intercourse, gives rise to anæmia, defective nutrition, muscular weakness, intellectual and nervous exhaustion. Young and healthy individuals recuperate rapidly after excesses of brief duration, as is often seen in young married pairs. Sickly and elderly persons, on the other hand, are much more severely affected by sexual excess, and recover therefrom but slowly if at all. Long continued sexual excesses ultimately wear out even the strongest.”