sed action, than those of the covered parts of our bodies, and
thus act with more energy from their irritative or sensitive associations
with the stomach. On this account in small-pox the eruption in consequence
of the previous affection of the stomach breaks out a day sooner on the
face than on the hands, and two days sooner than on the trunk, and recedes
in similar times after maturation.

But secondly, in weaker constitutions, that is, in those who possess less
sensorial power, so much of it is expended in the increased actions of the
fibres of the stomach excited by the stimulus of a meal, that a sense of
chilness succeeds instead of the universal glow above mentioned; and thus
the secondary part of the associated train of motions is diminished in
energy, in consequence of the increased activity of the primary part of it.

2. Another instance of a similar kind, where the secondary part of the
train acts with less energy in consequence of the greater exertions of the
primary part, is the vertigo attending intoxication; in this circumstance
so much sensorial power is expended on the stomach, and on its nearest or
more strongly associated motions, as those of the subcutaneous vessels, and
probably of the membranes of some internal viscera, that the irritative
motions of the retina become imperfectly exerted from deficiency of
sensorial power, as explained in Sect. XX. and XXI. 3. on Vertigo and on
Drunkenness, and hence the staggering inebriate cannot completely balance
himself by such indistinct vision.

3. An instance of the third circumstance, where the primary part of a train
of irritative motions acts with less, and the secondary part with greater
energy, may be observed by making the following experiment. If a person
lies with his arms and shoulders out of bed, till they become cold, a
temporary coryza or catarrh is produced; so that the passage of the
nostrils becomes totally obstructed; at least this happens to many people;
and then on covering the arms and shoulders, till they become warm, the
passage of the nostrils ceases again to be obstructed, and a quantity of
mucus is discharged from them. In this case the quiescence of the vessels
of the skin of the arms and shoulders, occasioned by exposure to cold air,
produces by irritative association an increased action of the vessels of
the membrane of the nostrils; and the accumulation of sensorial power
during the torpor of the arms and shoulders is thus expende