e length of time; some contrivance, therefore,
was necessary to guard against these accelerators of its destruction.
There are two ways in which the living body may be preserved; the one
by assimilating nutritious substances, to repair the loss of
different parts; the other to collect, in secretory organs, the
humours secreted from these substances.

We are admonished of the necessity of receiving substances into the
body, to repair the continual waste, by the appetites of hunger and
thirst. For the stomach being gradually emptied of its contents, and
the body, in some degree, exhausted by exercise, we experience a
disagreeable sensation in the region of the stomach, accompanied by a
desire to eat, at first slight, but gradually increasing, and at last
growing intolerable, unless it be satisfied.

When the fluid parts have been much dissipated, or when we have
taken, by the mouth, any dry food, or acrid substance, we experience
a sensation of heat in the fauces, and at the same time a great
desire of swallowing liquids. The former sensation is called hunger,
and the latter thirst.

From the back part of the mouth passes a tube, called the oesophagus
or gullet, its upper end is wide and open, spread behind the tongue
to receive the masticated aliment: the lower part of this pipe, after
it has passed through the thorax, and pierced the diaphragm, enters
the stomach, which is a membranous bag, situated under the left side
of the diaphragm: its figure nearly resembles the pouch of a bagpipe,
the left end being most capacious; the upper side is concave, and the
lower convex: it has two orifices, both on its upper part; the left,
which is a continuation of the oesophagus, and through which the food
passes into the stomach, is named cardia; and the right, through
which the food is conveyed out of the stomach, is called pylorus:
within this last orifice is a circular valve, which, in some degree,
prevents the return of the aliment into the stomach.

From the pylorus, or right orifice of the stomach, arise the
intestines, or bowels, which consist of a long and large tube, making
several circumvolutions, in the cavity of the abdomen; this tube is
about five or six times as long as the body to which it belongs.
Though it is one continued pipe, it has been divided, by anatomists,
into six parts, three small, three large. The three small intestines
are the duodenum, the jejunum, and the ileum; the duodenum commences
at the pylo