can take over the functions of an erotogenic zone...' The 'satis-
faction must have been previously experienced in order to have
left behind a need for its repetition'. The need for repetition of the
satisfaction reveals itself in 'a peculiar feeling of tension, possessing
rather, the character of unpleasure, and by a sensation of itching
or stimulation which is centrally conditioned and projected on to
the peripheral erotogenic zone'. ¹ Sexual excitation arises in
several ways, i.e. (a) as a reproduction of a satisfaction experienced
in connection with other organic processes -- e.g. feeding, defeca-
ting, urination; (b) through appropriate peripheral stimulation of
erotogenic zones and (c) as the result of various kinds of stimula-
tion which can arouse erotogenic effects in the skin -- mechanical
agitation of the body, muscular activities and also intense affective
processes and intellectual work. ² '...there are present in the
organism contrivances which bring it about that in the case of a
great number of internal processes sexual excitation arises as a
concomitant effect, as soon as the intensity of those processes
passes beyond certain quantitative limits. What we have called
the component instincts of sexuality are either derived directly
from these internal sources or are composed of elements both from
those sources and from the erotogenic zones.' Individual sexual
constitutions will vary according to the varying development of
the erotogenic zones and of the internal sources. ³

Freud describes how the main erotogenic zones, the oral, anal,
phallic are successively stimulated because of the organic functions
with which they are associated. He also says that the order in which
the various instinctual impulses come into activity seems to be
phylogenetically determined, so too does the length of time during
which they are able to manifest themselves before they succumb
to the effects of some freshly emerging instinctual impulse, or to
some typical repression. ⁴

Freud also stated that '...it may be supposed that, as a result
of an appropriate stimulation of the erotogenic zones, or in other
circumstances that are accompanied by an onset of sexual excita-
tion, some substance that is disseminated generally throughout the
organism becomes decomposed and the products of its decomposi-

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