serve greatly to heighten the emotional intensity of skin sensations. So
that, of all the great sensory fields, the field of touch is at once the
least intellectual and the most massively emotional. These qualities, as
well as its intimate and primitive association with the apparatus of
tumescence and detumescence, make touch the readiest and most powerful
channel by which the sexual sphere may be reached.

In disentangling the phenomena of tactile sensibility ticklishness has
been selected for special consideration as a kind of sensation, founded on
reflexes developing even before birth, which is very closely related to
sexual phenomena. It is, as it were, a play of tumescence, on which
laughter supervenes as a play of detumescence. It leads on to the more
serious phenomena of tumescence, and it tends to die out after
adolescence, at the period during which sexual relationships normally
begin. Such a view of ticklishness, as a kind of modesty of the skin,
existing merely to be destroyed, need only be regarded as one of its
aspects. Ticklishness certainly arose from a non-sexual starting-point,
and may well have protective uses in the young animal.

The readiness with which tactile sensibility takes on a sexual character
and forms reflex channels of communication with the sexual sphere proper
is illustrated by the existence of certain secondary sexual foci only
inferior in sexual excitability to the genital region. We have seen that
the chief of these normal foci are situated in the orificial regions where
skin and mucous membrane meet, and that the contact of any two orificial
regions between two persons of different sex brought together under
favorable conditions is apt, when prolonged, to produce a very intense
degree of sexual erethism. This is a normal phenomenon in so far as it is
a part of tumescence, and not a method of obtaining detumescence. The kiss
is a typical example of these contacts, while the nipple is of special
interest in this connection, because we are thereby enabled to bring the
psychology of lactation into intimate relationship with the psychology of
sexual love.

The extreme sensitiveness of the skin, the readiness with which its
stimulation reverberates into the sexual sphere, clearly brought out by
the present study, enable us to understand better a very ancient
contest--the moral struggle around the bath. There has always been a
tendency for the extreme cultivation of physical purity to lead