Harriet Martineau, at the beginning of her _Autobiography_,
referring to the vivid character of tactile sensations in early
childhood, remarks, concerning an early memory of touching a
velvet button, that "the rapture of the sensation was really
monstrous." And a lady tells me that one of her earliest memories
at the age of 3 is of the exquisite sensation of the casual
contact of a cool stone with the vulva in the act of urinating.
Such sensations, of course, cannot be termed specifically sexual,
though they help to furnish the tactile basis on which the
specifically sexual sensations develop.

The elementary sensitiveness of the skin is shown by the fact
that moderate excitation suffices to raise the temperature, while
Heidenhain and others have shown that in animals cutaneous
stimuli modify the sensibility of the brain cortex, slight
stimulus increasing excitability and strong stimulus diminishing
it. Féré has shown that the slight stimulus to the skin furnished
by placing a piece of metal on the arm or elsewhere suffices to
increase the output of work with the ergograph. (Féré, _Comptes
Rendus Société de Biologie_, July 12, 1902; id., _Pathologic des
Emotions_, pp. 40 et seq.)

Féré found that the application of a mustard plaster to the skin,
or an icebag, or a hot-water bottle, or even a light touch with a
painter's brush, all exerted a powerful effect in increasing
muscular work with the ergograph. "The tonic effect of cutaneous
excitation," he remarks, "throws light on the psychology of the
caress. It is always the most sensitive parts of the body which
seek to give or to receive caresses. Many animals rub or lick