considers that ticklishness "appears to be one of the simplest
developments of mechanical and automatic nervous processes in the
direction of the complex functioning of the higher centres which comes
within the scope of psychology,"[7] Stanley Hall and Allin remark that
"these minimal touch excitations represent the very oldest stratum of
psychic life in the soul."[8] Hirman Stanley, in a somewhat similar
manner, pushes the intellectual element in ticklishness very far back and
associates it with "tentacular experience." "By temporary self-extension,"
he remarks, "even low amoeboid organisms have slight, but suggestive,
touch experiences that stimulate very general and violent reactions, and
in higher organisms extended touch-organs, as tentacles, antennæ, hair,
etc., become permanent and very delicately sensitive organs, where minimal
contacts have very distinct and powerful reactions." Thus ticklishness
would be the survival of long passed ancestral tentacular experience,
which, originally a stimulation producing intense agitation and alarm, has
now become merely a play activity and a source of keen pleasure.[9]

We need not, however, go so far back in the zoölogical series to explain
the origin and significance of tickling in the human species. Sir J.Y.
Simpson suggested, in an elaborate study of the position of the child in
the womb, that the extreme excitomotory sensibility of the skin in various
regions, such as the sole of the foot, the knee, the sides, which already
exists before birth, has for its object the excitation and preservation of
the muscular movements necessary to keep the foetus in the most favorable
position in the womb.[10] It is, in fact, certainly the case that the
stimulation of all the ticklish regions in the body tends to produce
exactly that curled up position of extreme muscular flexion and general
ovoid shape which is the normal position of the foetus in the womb. We may
well believe that in this early developed reflex activity we have the
basis of that somewhat more complex ticklishness which appears somewhat