menopause, so that the woman really requires only about 300 to 350 ova on the average. This liberality on the part of Nature, however, does not begin to approach her lavishness in the case of seed of the male, for in his case while only one spermatozoon is required to fertilize an ovum (and in fact only one is permitted to do so), we find that in each normal act of ejaculation of semen by the male over 250,000 spermatozoa are projected.

The ripening and discharge of the egg from the Ovaries, and the consequent congestion above referred to, accompanied by what is called Menstruation, occurs regularly each lunar month (28 days). What is called Ovulation consists of the monthly maturing and expulsion of the ripe ovum or egg, while Menstruation (as we shall see later on) consists of the monthly discharge of blood and mucus from the inner surface of the Uterus; the two processes occur in connection with each other, yet neither can be considered as the cause of the other.

Menstruation. It may be well to call your attention at this point to the process known as Menstruation, or "the monthly flow," or "the courses" of women. Menstruation is the monthly flow of bloody fluid which occurs in all healthy (non-pregnant) women from puberty to the menopause or "change of life."

By "Puberty" is meant the age at which a woman begins her period of possible child-bearing experience. In temperate climates the average age of puberty is about fourteen years, while in tropical countries it is often a year or so earlier, and in arctic countries a year or so later. The time, however, depends materially upon the temperament, race, hygiene, and general environment of the individual girl. At this period the girl gradually changes into the young woman. Her figure changes, her bust develops, her hips broaden, and her mental and emotional nature undergoes a change. Also the menstrual flow begins to manifest at this time; at first scanty and irregular, but gradually changing into the characteristic flow each month.

At the period of puberty, the girl undergoes marked emotional changes. She becomes very "emotional" as a rule, and quite "sensitive." She becomes filled with strange, unaccountable longings, ideas, and "notions." She usually manifests a great emotional interest in her girl friends, and often manifests marked jealousy in connection with these friendships. The girl is apt to indulge in day-dreaming at this period, and becomes quite romantic and "flighty." She devours love stories, and delights in imagining herself as the heroine of similar adventures. The period from the beginning of puberty to that of the attainment of full sexual maturity is known as the period of "adolescence," and generally extends to about the age of eighteen in the case of girls.

By the Menopause is meant that period of the woman's "change of life," the average time of which is about the age of forty-five years, although this varies greatly in different individuals. As a rule, it is held that the period of the woman's child-bearing possibility extends over an average period of thirty years. At the Menopause the woman's reproductive activity declines and finally ends. The Ovaries diminish in size, the Graafian follicles cease to form and develop; the Fallopian Tubes atrophy; and there occur other physical, mental, and emotional changes in the woman. While the age of forty-five is held to be the average age at which the Menopause occurs in women, still it is not at all uncommon to find women who menstruate regularly up to the age of fifty, or fifty-two, or even fifty-five, while a large number of women menstruate regularly at the age of forty-eight.

Some women undergo little or no physical or emotional disturbance at the time of the Menopause. In such cases their periods become more or less irregular, with extending intervals between periods; the flow becomes more and more scanty; then several periods are skipped altogether; and finally the periods cease entirely. Other women, however, experience more or less physical disturbance during the years of the "change." They sometimes experience loss of appetite, or a capricious appetite, headaches, loss of weight, or else a sudden taking on of fatty tissue. They often become quite irritable and "notiony," and often become quarrelsome and pugnacious, and in some cases manifest unreasonable jealousy. But, in the opinion of many of the best authorities, much of this trouble comes from the mental expectancy of them by the woman, resulting from the notion that a woman must have these things happen to her. The power of the mind over the body is now well known, and we have here another instance of its effect. The remedy is obvious.

Another matter which disturbs the woman at this time, in many cases, is the common belief that after "the change" she will lose all of her sex attractiveness, and her sexual feelings, etc. This is a grave error, for the experience of all observing physicians is that no such results follow this period of the woman's life. Many women become even more attractive to the other sex after this time, by reason of acquiring a certain maturity and "ripeness" which proves very attractive to many men—often to young men as well as older ones. Moreover, the sexual desires do not cease with the cessation of the reproductive functions. On the contrary, it often happens that such emotions and desires are increased in the woman at, and after, this time of her life. So true is this that this period has been called "The Dangerous Age" for women, and the experience of many a woman of forty-five to fifty will corroborate this statement. The woman at this time should beware of contracting unwise love affairs and entanglements, and of yielding to impulses toward men other than her mate. A word to the wise should be sufficient in this case.

To return to the main subject of Menstruation, it may be said that the monthly flow, when once established, occurs at intervals of every twenty-eight days, on the average, although in some individual cases it occurs as often as every twenty-one days, while in others it occurs as seldom as once in every six weeks, all without exceeding the bounds of normal functioning. Menstruation ceases temporarily during pregnancy, in normal cases, and often also ceases during the period of lactation or nursing. The menstrual period lasts on an average for four or five days, the flow increasing for the first half of the period, and decreasing during the last half. At the beginning of the period there is often manifested a general congestion of all of the sexual organs of the woman, and often of the breasts as well. There is also usually found a sense of physical discomfort, from which more or less irritable feeling arises. In rare cases there are found severe cramps and pains, and in some cases the woman finds it necessary to call in medical aid, or to go to bed, or both. In such cases a cure is often worked by improving the general health, and by observing common sense hygienic rules.

Menstruation is caused by a hypertrophy of the mucus membrane of inner surface of the Uterus, which is followed by a shedding of the hypertrophied membrane. This leaves exposed the underlying vessels, which bleed. New mucus membrane is formed after the period. The menstrual flow consists of a thin, bloody fluid, having peculiar odor, in which is combined blood, thin skin, and mucus membrane, and also mucus from the Uterus and the Vagina, the blood being light in consistency and not clotted.

During the menstrual period the ovum, or egg, is discharged, and enters the Uterus, as we shall see presently.

The Life-History of the Ovum. The physiology of the remaining sexual organs of the woman may perhaps best be studied by considering the story of the Life-History of the Ovum, or human egg, for the functions of such