rus, and is continued into the jejunum, which is so called
from its being generally found empty: the ileum is only a
prolongation of the jejunum, and terminates in the first of the great
intestines, called the caecum. The other great guts are the colon and
the rectum.

The whole of what has been described is only a production of the same
tube, beginning at the oesophagus. It is called by anatomists the
intestinal canal, or prima via, because it is the first passage of
the food. It has circular muscular fibres, which give it a power of
contracting when irritated by distension; and this urges forward the
food which is contained in it. This occasions a worm like motion of
the whole intestines, which is called their peristaltic motion.

The mesentery is a membrane beginning loosely on the loins, and
thence extending to all the intestines; which it preserves from
twisting by their peristaltic motion. It serves also to sustain all
the vessels going to and from the intestines, namely the arteries,
veins, lacteals, and nerves; it also contains several glands, called,
from their situation, mesenteric glands.

The lacteal vessels consist of a vast number of fine pellucid tubes,
which arise by open mouths from the intestines, and proceeding thence
through the mesentery, they frequently unite, and form fewer and
larger vessels, which pass through the mesenteric glands, into a
common receptacle or bag, called the receptacle of the chyle. The use
of these vessels is to absorb the fluid part of the digested aliment,
called chyle, and convey it into the receptacle of the chyle, that it
may be thence carried through the thoracic duct into the blood.

The receptacle of the chyle is a membranous bag, about two thirds of
an inch long, and one third of an inch wide, at its superior part it
is contracted into a slender membranous pipe, called the thoracic
duct, because its course is principally through the thorax; it passes
between the aorta and the vena azygos, then obliquely over the
oesophagus, and great curvature of the aorta, and continuing its
course towards the internal jugular vein, it enters the left
subclavian vein on its superior part.

There are several other viscera besides those I have described, which
are subservient to digestion; among these may be mentioned the liver,
gall bladder, and pancreas. The liver is the largest gland in the
body, and is situated immediately under the diaphragm, principally on
the right side. I