organ, and the immediate aim of the impulse lies in the elimination of
this organic stimulus.

Another preliminary assumption in the theory of the impulse which we
cannot relinquish, states that the bodily organs furnish two kinds of
excitements which are determined by differences of a chemical nature.
One of these forms of excitement we designate as the specifically sexual
and the concerned organ as the _erogenous zone_, while the sexual
element emanating from it is the partial impulse.[27]

In the perversions which claim sexual significance for the oral cavity
and the anal opening the part played by the erogenous zone is quite
obvious. It behaves in every way like a part of the sexual apparatus. In
hysteria these parts of the body, as well as the tracts of mucous
membrane proceeding from them, become the seat of new sensations and
innervating changes in a manner similar to the real genitals when under
the excitement of normal sexual processes.

The significance of the erogenous zones in the psychoneuroses, as
additional apparatus and substitutes for the genitals, appears to be
most prominent in hysteria though that does not signify that it is of
lesser validity in the other morbid forms. It is not so recognizable in
compulsion neurosis and paranoia because here the symptom formation
takes place in regions of the psychic apparatus which lie at a great
distance from the central locations for bodily control. The more
remarkable thing in the compulsion neurosis is the significance of the
impulses which create new sexual aims and appear independently of the
erogenous zones. Nevertheless, the eye corresponds to an erogenous zone
in the looking and exhibition mania, while the skin takes on the same
part in the pain and cruelty components of the sexual impulse. The skin,