_Courty_ enumerates as prodromal symptoms which are observed in the majority of girls before the first appearance of menstruation: swelling and tenderness of the breasts, sensation of fulness and weight in the hypogastric region, moderate intestinal meteorism, sacrache, aqueo-mucous vaginal discharge, finally, an itching sensation in the genital organs. These manifestations may also assume a morbid character, taking the form of violent abdominal and lumbo-sacral pain, general fatigue and weakness, dyspepsia and diarrhœa, cephalalgia, various kinds of neuralgia, some degree of moral aberration. After the first menstruation, two or three months may elapse before the girl menstruates again, but after the lapse of a year the flow usually recurs at quite regular periods. Sometimes the early periods are very violent and recur very frequently, every twenty days, for instance. The greatest increase in size and weight occurs in the female sex at the time of the menarche. Amongst the poorer classes the greatest development in size and strength occurs between the ages of 13 and 15 years, whereas in the upper classes of society, those who ultimately attain the same weight exhibit their greatest growth at the ages of 12, 13, and 14 years. According to _Pagliani_ the greatest growth in the female sex always precedes puberty, so that for example a girl who begins to menstruate at the age of 12 will grow most rapidly in the year preceding this, whereas a girl who begins to menstruate at a more advanced age will not undergo her most rapid phase of growth so early as the age of 11. According to the observations of _Bowditch_, _A. Hey_, _Lombroso_, _Pagliani_, and _Ploss_, up to the age of 11 or 12 years the growth of girls exceeds that of boys, but whereas in girls growth ceases suddenly at the age of 14, in boys growth proceeds regularly up to the age of 16 years. At birth boys are on the average 1 cm. (⅖″) longer than girls; but during puberty the female sex catches up the male in height, or even surpasses it. According to _Ploss_, a girl of 16 or 17 years is as tall as a young man of 18 or 19 years. The earlier development of the female as compared with the male at the time of puberty is a constant phenomenon, to be observed in all races, in every climate, and in all strata of society. According to the statistical data published by the authors just quoted, the age of greatest development in the respective sexes is: _In the female._ _In the male._ As regards weight at the age of 12 to 14 years. 14 to 17 years. As regards height at the age of 12 to 13 years. 12 to 15 years. As regards respiratory capacity at the age of 12 to 15 years. 15 to 17 years. As regards muscular strength at the age of 12 to 14 years. 14 to 15 years.