_The concubitalis function of the uterus._—Another highly important function of the uterus is to serve as an organ of copulation. During the orgasm, at the moment of the highest excitement, the uterus descends deeper into the small pelvis.[J] It is assisted in the descent by the pressure of the abdominal muscles. The uterus, usually flattened in the sagittal direction, assumes a round, pear-shaped form during the orgasm and for some time afterwards. In this way a real cavum uteri is produced, and through the vacuum thus produced, the uterus is able to suck in the semen by means of aspiration. Furthermore, through the excitation, the circular fibres of the cervix contract at the same time as the longitudinal fibres. The result is a dilatation of the cervical orifice. The formerly flat opening becomes round. At the same time the uterine orifices of the tubes, which are generally closed, open widely and challenge the entrance of the spermatozoa. _Female ejaculation._—The contraction of the cervical fibres also causes the erection of the vaginal portion and of the neck of the uterus. This erection, at the moment of the highest orgasm, serves to expel Kristeller’s slimy plug from the cervix. This expulsion represents female ejaculation. After the expulsion the cervix becomes soft and flabby. The erection and sudden relaxation of the cervix cause the external os to open, sometimes to the extent of fully three centimeters, and to make several successive gasps. Each time the gasp draws powerfully the external os into the cervix and causes the aspiration of the semen. _Function of the vagina._—The function of the vagina is to serve as a receptacle of penis and semen. The erectile tissue which runs along the entire length between the different membranes, forming the vaginal wall, helps the vagina to adjust itself to the volume of the penis and to augment its turgescence. The muscular fibres, situated within the tunica media of the vaginal mucous membrane, contract during the ejaculation of the semen. The contraction is of a peristaltic nature, starting from the vaginal aperture. In this way the semen is stowed toward the uterine orifice under a certain pressure and is prevented from flowing off. Previous to this contraction the sphincter cunni, the analogous muscle to the musculus bulbo-cavernosus in the male, also contracts and clinches the penis, pressing, at the same time, upon the two bulbs of the vestibule. In this way the vaginal orifice is more firmly compressed.