Hitherto we have occupied ourselves with the description of the peripheral sexual organs, and of the processes of detumescence. We must now pass on to the second group of sexual phenomena, the processes of contrectation. Even in childhood, these processes play an important part; indeed, they generally manifest themselves at an earlier age than the processes of detumescence. But first, let me briefly summarise Max Dessoir's account of the stages of the sexual impulse--stages in which the contrectation impulse is alone concerned. In its development, three stages may be distinguished. One of these is the neutral stage, in earliest childhood, in which, speaking generally, the processes of contrectation are not yet to be observed, and during which the child does not feel attracted towards anyone in such a manner as to make it necessary for us to assume the occurrence of any psychosexual process. This stage is succeeded by the extremely important undifferentiated stage, to which Max Dessoir[34] has drawn attention. Its principal characteristic is indicated in its name: the direction of the impulse is not yet completely differentiated. It oscillates to and fro, and depends upon the external objects which happen to be in the vicinity. This undifferentiated stage is of profound importance; and owing to the fact that its existence has been ignored in the study of sexual perversions, great confusion has arisen. During the undifferentiated period, it may happen that quite normal children exhibit homosexual excitement, whose importance is apt to be greatly over-estimated by their relatives and others. During the undifferentiated stage a boy may love one of his teachers or one of his friends, and yet in later life be perfectly normal; many a woman, again, who loves her husband ardently has earlier, during the undifferentiated period, passionately loved a school-fellow or a governess. On the other hand, during the undifferentiated stage a boy may exhibit an inclination towards someone of the opposite sex, the governess or the girl-friend of his sister, for instance; conversely, the girl may be attracted by a boy or a young man. This inclination, whether homosexual or heterosexual, often leads to bodily acts, to contact with the beloved person, embraces, and kisses, without the necessary occurrence of any manifestations on the part of the external genital organs, although such manifestations may at times ensue. The undifferentiated stage is followed by the third stage, in which the contrectation impulse becomes differentiated, so that in normal individuals the sexual impulse becomes unmistakably heterosexual. Normally, this differentiated stage endures until the time of the final extinction of the sexual impulse.