use; the action of the muscles of deglutition is
the proximate effect; the pushing the food into the stomach is the remote
effect; and the nutrition of the body is the post-remote effect.

Though the muscles subservient to deglutition have their actions previously
associated, so as to be excited into synchronous tribes or successive
trains, either by volition, as when we swallow a disagreeable drug; or by
sensation, as when we swallow agreeable food; or by irritation, as when we
inattentively swallow our saliva; yet do all those three kinds of
deglutition belong to the respective classes of volition, sensation, and
irritation; because the first links of these tribes or trains of muscular
action are excited by those sensorial powers, and the associated links,
which accompany or succeed them, are excited by the combined powers either
of volition, or of sensation, or of irritation, along with that of
association.

2. _Respiratio._ Respiration is immediately caused by the sensorial power
of sensation in consequence of the baneful want of vital air; and not from
the accumulation of blood in the lungs, as that might be carried on by
inhaling azote alone, without the oxygenous part of the atmosphere. The
action of respiration is thus similar to that of swallowing our food to
appease the pain of hunger; but the lungs being surrounded with air, their
proper pabulum, no intermediate voluntary exertions are required, as in
hunger, to obtain and prepare the wanted material.

Respiration is similar to slow combustion; the oxygenous part of the
atmosphere is received through the moist membranes, which line the
air-cells of the lungs, and uniting with the inflammable part of the blood
generates an acid, probably the phosphoric acid; a portion of carbonic acid
is likewise produced in this process; as appears by repeatedly breathing
over lime-water, which then becomes turbid. See Botanic Garden, P. I. Canto
I. l. 401. note.

3. _Sternutatio._ Sneezing consists of muscular actions produced by the
sensorial faculty of sensation; and is an effort to dislodge, by means of
air forcibly impelled through the nostrils, some material; which stimulates
the membrane, which lines them, into too great action, and might thence
injure the sense of smell which is diffused on it.

In this operation the too great action of the vessels of the membrane of
the nostrils is the remote cause; the sensation thence induced is the
proximate cause; and the mus