pleasure is experienced only when certain conditions are fulfilled. Contact with the male genital organs stimulates in the female the sensory nerves of the vulva, the vestibule, and the vagina; the nervous stimulus is transmitted to the cerebral cortex, where it gives rise to the sensation of sexual pleasure, and causes, through the intermediation of the genito-spinal centre, a number of reflex actions. As sensory nerve terminals of such reflex arcs, the final ramifications of the pudic branch of the sciatic plexus play the most important part; in the clitoris these nerves are beset with a peculiar kind of end-bulbs, the genital corpuscles discovered by _W. Krause_; from their structure these corpuscles seem admirably adapted to respond to the very slightest stimulation, producing voluptuous sensations and perceptions, and giving rise to various reflex manifestations. The first part of the path of the afferent impulses by which sexual pleasure is aroused is constituted by the dorsal nerves of the clitoris. The reflex changes consequent upon sexual excitement begin already in the vestibule, inasmuch as the secretion of Bartholin’s glands, which are compressed by the action of the constrictor cunni muscle, is expelled during coitus, the secretion, owing to the situation of the orifices of Bartholin’s ducts, passing over the external genitals. The clitoris becomes erect; the blood in the bulbs of the vestibule, the venous plexus situated around the margin of the vestibule along the boundary between the labia majora and the labia minora, is pressed into the glans clitoridis, the erection and sensibility of this structure being proportionately heightened. By the action of the constrictor cunni and ischiocavernosus muscles, the clitoris, the distal extremity of which is bent downwards at a right angle, is drawn down and pressed against the penis. At the entrance of the vagina is the sphincter vaginæ muscle, whose action is reinforced by muscular fibres running in the middle coat of the vagina itself. It is probable that the muscular activity of the vagina and the uterus facilitates the entrance of the semen into the cavity of the uterus.