Preceding the first menstruation an ovary is considerably enlarged, becomes of a red color, and its vascular apparatus is considerably congested; the Fallopian tube also becomes congested; its fimbriated extremity is of a violet red color, and has a velvety appearance. The Graafian vesicles increase in size; fifteen or twenty of them, more advanced than the others, project from the surface of the ovary; one of these grows so that after a few days it forms a tumor of the size of a cherry; the walls of the vesicle, being distended by an increased secretion of fluid, becomes quite thin, and at last are ruptured. When the thinned walls give way, the ovule is expelled, with a part of the granular contents of the vesicle; these are grasped by the fimbriated extremity of the Fallopian tube which is prepared to receive it and convey it through its canal into the cavity of the uterus. This evolution of an ovule excites numerous sympathies throughout the organism of the female, and especially the generative organs. The vascular apparatus of the womb becomes developed in an unusual manner; a network of fine blood vessels surround the orifices of the numerous glandular tubes, of which the membrane is almost entirely composed; this gives a violet hue to the internal surface of the womb; the utricular glands increase in size, the muscular structure of the uterus acquires greater extension, becomes redder and more spongy and supple, the volume of the organ is increased, the neck is tumefied and its orifice narrower, the lips of the os tincæ are warmer and their color deeper. The vascular congestion which the uterus undergoes is accompanied with the exudation of sanguineous fluid, which is at first but a few drops; this communicates to the increased vaginal mucus a reddish hue. After a day or two there is a bloody flow from the vascular network of the mucous membrane. This flow, which constitutes the menses, is diminished after three or four days, and the discharge again contains a large proportion of mucus and serum. It is probable that the rupture of a Graafian vesicle occurs during the last days of the flow, ordinarily, and it is also believed that venereal excitement is capable of exerting so much influence upon it that it may determine the rupture of an enlarged vesicle, which, without sexual intercourse, would have remained whole several days longer. After the discharge of the ovule consequent on the rupture of the Graafian vesicle, the walls of the vesicle contract on the matter that is effused within it, and form a compact mass, which after a time has an orange yellow color—this is called the _corpus luteum_.