n had not usually produced
sensation, this new sensorial power, added to the irritation occasioned by
the stimulus, increases the activity of the organ. And if this activity be
catenated with the diurnal circle of actions, an increasing inflammation is
produced; as in the evening paroxysms of small-pox, and other fevers with
inflammation. And hence schirrous tumours, tendons and membranes, and
probably the arteries themselves become inflamed, when they are strongly
stimulated.

IV. _Of Stimulus greater than natural._

1. A quantity of stimulus greater than natural, producing an increased
exertion of sensorial power, whether that exertion be in the mode of
irritation, sensation, volition, or association, diminishes the general
quantity of it. This fact is observable in the progress of intoxication, as
the increased quantity or energy of the irritative motions, owing to the
stimulus of vinous spirit, introduces much pleasurable sensation into the
system, and much exertion of muscular or sensual motions in consequence of
this increased sensation; the voluntary motions, and even the associate
ones, become much impaired or diminished; and delirium and staggering
succeed. See Sect. XXI. on Drunkenness. And hence the great prostration of
the strength of the locomotive muscles in some fevers, is owing to the
exhaustion of sensorial power by the increased action of the arterial
system.

In like manner a stimulus greater than natural, applied to a part of the
system, increases the exertion of sensorial power in that part, and
diminishes it in some other part. As in the commencement of scarlet fever,
it is usual to see great redness and heat on the faces and breasts of
children, while at the same time their feet are colder than natural;
partial heats are observable in other fevers with debility, and are
generally attended with torpor or quiescence of some other part of the
system. But these partial exertions of sensorial power are sometimes
attended with increased partial exertions in other parts of the system,
which sympathize with them, as the flushing of the face after a full meal.
Both these therefore are to be ascribed to sympathetic associations,
explained in Sect. XXXV. and not to general exhaustion or accumulation of
sensorial power.

2. A quantity of stimulus greater than natural, producing an increased
exertion of sensorial power in any particular organ, diminishes the
quantity of it in that organ. This appears from