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.