Thus, among the 150 prostitutes, 65 were less than 16 years of age. _Parent-Duchatelet_ found among 3,517 prostitutes under official observation, 5.6 per cent. under 17 years of age. There were: 2 prostitutes under 10 years of age. 3 prostitutes under 11 years of age. 3 prostitutes under 12 years of age. 6 prostitutes under 13 years of age. 20 prostitutes under 14 years of age. 51 prostitutes under 15 years of age. 111 prostitutes under 16 years of age. _Martineau’s_ observations also showed that in nearly all prostitutes the first coitus took place in very early youth. Of 607 prostitutes there were 489 in whom defloration had occurred between the ages of 5 and 20 years. According to _Grimmaldi_ and _Gurrieri_ defloration usually takes place in prostitutes before they attain the age of 10 years. Sometimes we find increased sexuality in early life as a pathological manifestation—psychopathia sexualis. Thus, _Esquirol_ records the case of a little girl aged four years who undertook improper manipulations in association with little boys. A female prisoner, _Lombroso_ writes, had at the age of six years practiced mutual masturbation with her brother aged seven, and at the age of eight years underwent defloration; another murderess, while still a schoolgirl, had conducted herself after the manner of an experienced prostitute. _Laurent_ reports the case of a girl who from the age of ten was engaged in sexual malpractices with her brothers and sisters, and finally underwent defloration at the age of fifteen. In many cases premature sexual development is manifested by enlargement of the breasts and growth of the axillary and pubic hair, and yet menstruation fails to appear. Thus, _Kussmaul_ has observed girls who while yet children exhibited all the external characteristics of sexually mature women, but who had not yet begun to menstruate. _Ploss_ has published a photograph showing in a girl five years of age the mons Veneris and the labia majora developed like those of a full-grown young woman, and covered with long thick hair; in this case, however, not only had menstruation not yet begun, but the breasts were still in the infantile condition.