[Illustration: Fig. 8 _B_.—Lobules and duct of the mammary gland. (Lenoir and Tarnier.)] The perineal body is flattened out and compressed by the passage of the head and in many cases torn. (Thirty per cent of primiparas and ten to fifteen per cent of multiparas.) It should be repaired immediately. =The Mammary Glands.=—The mammary glands are secondary but highly important parts of the genital system. They are formed by a dipping down of skin glands and they perform the special function of secreting milk. The breast is made up of fifteen or twenty lobes, each of which, like a bunch of grapes, clusters about and discharges into a single tube which, in turn, leads to the nipple. The area between the lobes is filled with fat and connective tissue. [Illustration: Fig. 9.—Nipple, areola, and the glands of Montgomery. (Eden.)] The _nipple_ is pink or darkly pigmented. It is composed of erectile tissue and under stimulation, it rises from the surface of the gland so that it is easily taken into the mouth. [Illustration: Fig. 10.—Supernumerary milk glands in the axillæ. They may be found also below the breasts. (Witkowski.)] [Illustration: Fig. 11.—The three ages of the breast—virginity, maturity, and senescence. (Witkowski.)] Surrounding the nipple is a darkly pigmented area from one inch to four inches in diameter that is called the _areola_. It contains hard, shot-like nodules, the glands, or tubercles, of Montgomery. These often secrete milk and sometimes become infected. It occasionally happens that more than two breasts may be found on the human female, and not infrequently pieces of mammary tissue may be discovered in the axilla or on the chest or back. The mammary gland is undeveloped at birth, but, nevertheless it may fill with milk (witches’ milk). At puberty, after marriage, and during pregnancy, the gland reaches maturity. It is only after delivery, however, that the functional climax is attained. CHAPTER II PHYSIOLOGY =Ovulation.=—Ovulation is the process whereby the eggs are discharged from the Graafian follicle which matures and protects them in the ovary. The egg is a true cell with one, and sometimes more than one, nucleus. The ripening of the eggs, as well as their discharge, is attended with much general disturbance and great physical changes. This phenomenon begins from the twelfth to the fifteenth year, depending on race, climate, occupation and temperament, and marks the transition of the individual from childhood into maturity. This period is called _puberty_. At this time the breasts enlarge, the hips round out, the vagina, uterus and external genitals increase in size. Hair appears upon the vulva, the emotions become more evident, and modesty develops through a consciousness of sexual difference and attraction. Simultaneously a new function appears—