the sexually mature woman recurs at four-weekly intervals, also gives rise to certain permanent changes in the ovaries. The site of each ruptured Graafian follicle becomes cicatrised, and in consequence of the formation of these little scars, the ovary no longer retains the smoothness of surface which was characteristic of the organ in childhood. From birth onwards the ovaries gradually increase in size, but the growth is disproportionate in different diameters. Thus, for instance, during the eighth year of life, growth is chiefly in thickness, so that the ratio between the length and the thickness becomes less than before. The structure of the ovaries also varies at different ages. In a girl of three years, the primitive ovarian follicles number about 400,000; at the age of eight it is estimated that their number has been reduced to about 36,000. Certainly the majority of the primitive follicles come to nothing. True Graafian follicles, of which an account has already been given, are not usually formed prior to the beginning of the puberal development; occasionally, however, they are formed in the ovaries of immature girls. Let us now pass to the consideration of the sexual impulse. We learn from personal observation that two entirely distinct processes participate in this impulse. In the first place, we have the physical processes that take place in the genital organs; these are in part unperceived, but in part they affect consciousness in the form of common sensations, or as ordinary tactile and other similar sensations. In the second place, we have those higher psychical processes by means of which man is attracted to woman, and woman to man. In our actual experience of the normal sexual life, both these groups of processes do, as a matter of fact, work in unison; but not only is it possible for us to distinguish them analytically; it is, in addition, possible in many instances to observe them in action clinically isolated each from the other. A long while ago I utilised this distinction for the analysis of the sexual impulse, describing the impulse in so far as it was confined to the peripheral organs as the _detumescence-impulse_ (from _detumescere_, to decrease in size), and in so far as it takes the form of processes tending towards bodily and mental approximation to another individual, as the _contrectation-impulse_ (from _contrectare_ to touch, or to think about). The distinction will become clearer to our minds if we familiarise ourselves first with cases in which either process occurs independently of the other. The detumescence-impulse is sometimes the sole manifestation of the sexual impulse. Certain idiots practise masturbation as a physical act, because sensations proceeding from the genital organs impel them to do so, precisely as itching of an area of the skin impels us to scratch. They masturbate without thinking of another person, and they feel no impulsion whatever towards sexual contact with another person.