that no
other liquid will equally well subserve the process of digestion and
promote health.

After the food is in the condition ready to be swallowed, by an
apparently involuntary motion, it is placed upon the back of the
tongue, which carries it backwards to the top of the pharynx, where
the constrictions of the pharynx, aided by the muscles of the tongue
and floor of the mouth, with a sudden and violent movement thrust it
beyond the epiglottis, in order to allow the least necessary time to
the closure of the glottis, after which, by the compression of the
oesophagus, it is forced into the stomach.

Here it is that the true business of digestion commences. For as soon
as any substance except water enters the stomach, this organ, with
involuntary movements, that seem almost like instinct, commences the
secretion of the gastric juice, and by long-continued contractions of
its muscular coat, succeeds in effecting a most perfect mixture of the
food with this juice, by which the contents of the stomach are reduced
to the softest pulp.

The gastric juice, in its pure state, is a colorless, transparent
fluid; "inodorous, a little saltish, and perceptibly acid. It
possesses the property of coagulating albumen, and separating the whey
of milk from its curd, and afterwards completely dissolving the curd.
Its taste, when applied to the tongue, is similar to that of
mucilaginous water, slightly acidulated with muriatic acid." The
organs of its secretion are an immense number of tubes or glands, of a
diameter varying from one five hundredth to one three hundredth of an
inch, situated in the mucous coat of the stomach, and receiving their
blood from the gastric arteries. A chemical analysis shows it to
consist of water, mucilage, and the several free acids--muriatic,
acetic, lactic, and butyric, together with a peculiar organic matter
called _pepsin_, which acts after the manner of ferments between the
temperature of 50 deg. and 104 deg. F.

The true process of digestion is probably owing to the action of
pepsin and the acids, especially if the presence of the chloro-hydric
or muriatic be admitted; since we know, by experiments out of the
body, that chlorine, one of its elements, is a powerful solvent of all
organic substances.

The antiseptic properties of the gastric juice, as discovered by
experiments made on Alexis St. Martin, doubtless have much influence
on digestion, although their true uses are probably not yet know