Unquestionably, many of the processes of childhood are not to be regarded as sexual, although they are closely related to the sexual life. This statement applies to many of the friendships between boys or between girls, such as are formed during the period in which the sexual impulse is still undifferentiated, or after its differentiation has occurred--and such friendships must not be identified with sexual feelings. At this period of life, we occasionally observe a desire in boys to form romantic friendships with others of their own sex; and the same is true also of girls. In many cases of this kind, there is no question of the presence of any sexual element, and we have no right, therefore, to regard as manifestations of the sexual impulse such instances of enthusiastic friendship during the period of undifferentiated sexual impulse. Each case must be separately analysed, in order to determine its nature. On the other hand, the sexual character of an inclination may sometimes be recognised in the early years of childhood, even in cases in which the boy's own genital organs are in no way involved. It may happen that a boy of eight will display a marked interest in the genital organs of youths or of men, and will seize every opportunity of peeping at them; and in such a case we are as a rule justified in assuming the existence of a homosexual tendency, even when there is no reflection of sexual disturbance to the boys own genital organs. But we must guard against the mistake of seeing a sexual element in every friendship between boys. As with human beings, so also with the lower animals, it is not always possible to differentiate friendship from the sexual impulse. Robert Mueller has collected a number of interesting observations bearing on this matter.[60] He states that the so-called animal friendships, friendships between animals of different species, are in many cases determined by sexual feelings. He mentions the case of a dog ten months old, which made sexual attacks on hens, and thereby killed them; in another instance, a thorough-bred dog, two years old, exhibited a similar perversion, and had a lasting sexual relationship with a hen. He also quotes a case of which a man named P. Momsen was the witness, in which a gander attempted to pair with a bitch. These examples show that in the cases of animal friendship so often reported in the newspapers, the existence of an element of perverse sexuality is at least possible. But it does not, of course, follow that every strange animal friendship is of a sexual nature.