Sexual Utilization of the Mucous Membrane of the Lips and Mouth.—­The significance of the factor of sexual overestimation can be best studied in the man, in whom alone the sexual life is accessible to investigation, whereas in the woman it is veiled in impenetrable darkness, partly in consequence of cultural stunting and partly on account of the conventional reticence and dishonesty of women.

The employment of the mouth as a sexual organ is considered as a perversion if the lips (tongue) of the one are brought into contact with the genitals of the other, but not when the mucous membrane of the lips of both touch each other.  In the latter exception we find the connection with the normal.  He who abhors the former as perversions, though these since antiquity have been common practices among mankind, yields to a distinct feeling of loathing which protects him from adopting such sexual aims.  The limit of such loathing is frequently purely conventional; he who kisses fervently the lips of a pretty girl will perhaps be able to use her tooth brush only with a sense of loathing, though there is no reason to assume that his own oral cavity for which he entertains no loathing is cleaner than that of the girl.  Our attention is here called to the factor of loathing which stands in the way of the libidinous overestimation of the sexual aim, but which may in turn be vanquished by the libido.  In the loathing we may observe one of the forces which have brought about the restrictions of the sexual aim.  As a rule these forces halt at the genitals; there is, however, no doubt that even the genitals of the other sex themselves may be an object of loathing.  Such behavior is characteristic of all hysterics, especially women.  The force of the sexual impulse prefers to occupy itself with the overcoming of this loathing (see below).

Sexual Utilization of the Anal Opening.—­It is even more obvious than in the former case that it is the loathing which stamps as a perversion the use of the anus as a sexual aim.  But it should not be interpreted as espousing a cause when I observe that the basis of this loathing—­namely, that this part of the body serves for the excretion and comes in contact with the loathsome excrement—­is not more plausible than the basis which hysterical girls have for the disgust which they entertain for the male genital because it serves for urination.

The sexual role of the mucous membrane of the anus is by no means limited to intercourse between men; its preference has nothing characteristic of the inverted feeling.  On the contrary, it seems that the pedicatio of the man owes its role to the analogy with the act in the woman, whereas among inverts it is mutual masturbation which is the most common sexual aim.