In the female sex, also, there are notable differences in the condition of the genital organs between the adult and the child. In the first place, the relative sizes of the various organs differ greatly. But other differences are also noticeable, not dependent, however, on differences in age, but on whether there has or has not been experience of sexual intercourse, and on whether pregnancy and parturition have occurred. When we compare a female child with an adult woman, the first obvious difference is in the shape of the external genital organs. In the child, the vulva is placed much higher and more to the front, so that it is distinctly visible even when the thighs are in close apposition. In the child, also, the labia majora are less developed, for as womanhood approaches a great deposit of fat takes place in these structures. Again, in the child, the outer surfaces of the labia majora and that part of the skin of the abdomen just in front of the labia (the _mons veneris_) are as hairless as the rest of the body, whereas in the adult woman these regions are covered with the pubic hair. According to Marthe Francillon,[10] to whom we are indebted for an elaborate study of puberty in the female sex, during the puberal development changes occur also in the clitoris. The genital corpuscles of Krause and the corpuscles of Finger (_Wollustkoerperchen_), the terminals of the nerves passing to the erectile tissue of the clitoris, undergo at this time a marked increase in size. The clitoris itself, hitherto comparatively small, now attains a length of three to four centimetres (1.2 to 1.6 inch), in the quiescent state, and of four and a half to five centimetres (1.8 to 2 inches) when erect. In the virgin also, as previously mentioned, the hymen is present, a structure of very variable form. After defloration its remnants persist in the form of small prominences around the margin of the vaginal inlet (_carunculae myrtiformes_). But, quite independently of defloration, in the child the vaginal orifice is much smaller than in the riper girl. The uterus undergoes remarkable changes. In the foetus, during the latter part of intra-uterine life, this organ grows very rapidly; but immediately after birth its growth is arrested, so that in a girl of nine it is little larger than in the new-born infant. During the period of puberal development, however, the growth of the organ is once more extremely rapid. Its shape also changes at this time. In the child, the uterus is longer in proportion to its thickness; in childhood, too, the comparative length of the cervix in relation to that of the body of the organ is much greater than in the adult woman. We need only allude in passing to the fact that later in life marked changes occur in the uterus as a result of pregnancy and parturition. The hyperaemia and the bleeding that take place periodically during menstruation lead to certain changes in the mucous surface of the uterus. Ovulation, which in