MENSTRUATION. In healthy women at the period of puberty, a certain amount of sanguineous fluid is secreted by the lining membrane of the uterus, and is excreted through the vagina every month; this is termed the catamenia, or menses, and the function itself menstruation. A female in whom the discharge recurs at the usual periods, in the usual quantity, and of the usual quality, is said to be regular, The occurrence of menstruation defines the period of puberty at which a girl becomes a woman capable of conception, and its cessation terminates the prolific period of female life. Dr. Robinson, of Manchester, England, in a paper on the natural history of menstruation, has stated the age at which it occurred in 450 cases. According to his table, 10 menstruated for the first time at 11 years of age, 19 at 12, 53 at 13, 85 at 14, 97 at 15, 76 at 16, 57 at 17, 26 at 18, 23 at 19, and 4 at 20. The time at which the first menstruation occurs varies exceedingly from the influence of climate, habits of life and constitution. There have been occasional instances of very precocious menstruation, in which the first appearance of the discharge was attended with all the attributes of puberty. I myself knew one case where a girl of nine years, not only menstruated, but presented the external signs of puberty, such as prominent breasts, wide pelvis, rounded contour of body, &c. The first appearance of the menses very rarely occurs without being preceded by premonitory symptoms. There is usually a degree of languor and lassitude, fatigue after exertion, inequality of spirits, dark shade under the eyes, headache, sometimes pain in the thyroid gland, pain in the back, a sensation of tension and swelling in the lower part of the abdomen, and occasionally considerably fever. Not unfrequently strange nervous disturbances occur; but all of these symptoms may pass off, the first and second time, without the appearance of the menses, or with a white discharge only. Usually the phenomena may last from one to eight days, then there is an abundant flow of mucus, which after one or two days is mixed with blood, and soon gives place to almost pure blood. When this discharge takes place most of the unpleasant symptoms disappear, and the female only complains of weakness and is somewhat pale. The hemorrhage continues for several days, then the amount of blood mingled with the vaginal mucosities diminishes, soon there is mucus alone, then the discharge ceases. I should remark now that the propriety of applying the terms, blood or hemorrhage, to the menstrual secretion is properly questioned. Sometimes the first menstruation takes place without being preceded by any discomfort, but pretty generally there is a change in the girl at the time, both in her body and mind, a change that fits her for the important duties that devolve upon her.