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into nearly perpetual action, as the conglomerate and capillary glands; and
others into actions still somewhat less frequent, as the alimentary canal,
and the lacteal and lymphatic absorbents with their conglobate glands: all
these are principally actuated by the sensorial powers of irritation, and
of association; but in some degree or at some times by those of sensation,
and even of volition. There are three kinds of stimulus, which may easily
be occasionally diminished, that of heat on the skin, of food in the
stomach, and of the oxygenous part of the atmosphere, which mixes with the
blood in respiration, and stimulates the heart and arteries.

2. When any parts, which are naturally excited into perpetual action by
stimulus, become torpid or less active from decrease of that stimulus;
there first occurs a decrease of the activity of the parts next catenated
with them; thus going into cold water produces a torpor of the capillary
vessels of the lungs, as is known by the difficult respiration, which
immediately occurs; for the sensorial power of association, which naturally
contributes to actuate the lungs, is now less excited by the decreased
actions of the cutaneous vessels, with which they are catenated. This
constitutes the cold fit of fever.

There next occurs an accumulation of the sensorial power of irritation in
the parts, which were torpid from defect of stimulus, as the cutaneous
vessels for instance when exposed to cold air; and a similar accumulation
of the sensorial power of association occurs in the parts which were
catenated with the former, as the vessels of the lungs in the example above
mentioned. Whence, if the subduction of stimulus has not been too great, so
as to impair the health of the part, the activity of the irritative motions
returns, even though the stimulus continues less than usual; and those of
the associate motions become considerably increased, because these latter
are now excited by the previous fibrous motions, which now act as strong or
stronger than formerly, and have also acquired an accumulation of the
sensorial power of association. This accounts for the curious event of our
becoming warm in a minute or two after remaining in water of about 80
degrees of heat, as in the bath at Buxton; or in the cold air of a frosty
morning of about 30 degrees of heat.

But if the parts thus possessed of the accumulated sensorial powers of
irritation and of association be exposed again to the