and
stomach, to the left side under the name of the transverse colon. At
the left side, it turns, and descends to the left haunch-bone, and is
called the descending colon. Here it makes a peculiar curve upon
itself, which is called the _sig'moid flex'ure_.

[Illustration: Fig. 61. 1, 1, The duodenum. 2, 2, The small intestine. 3,
The junction of the small intestine with the colon. 4, The appendix
vermiformis. 5, The caecum. 6, The ascending colon. 7, The transverse
colon. 8, The descending colon. 9, The sigmoid flexure of the colon. 10,
The rectum.]

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250. Describe the course of the divisions of the colon. Explain fig.
61.

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251. The RECTUM is the termination of the large intestine. The large
intestine has three coats, like the stomach and small intestine. The
longitudinal fibres of the muscular coat are collected into three
bands. These bands are nearly one half shorter than the intestine, and
give it a sacculated appearance, which is characteristic of the caecum
and colon.

252. The LACTEALS are minute vessels, which commence in the villi,
upon the mucous surface of the small intestine. From the intestine
they pass between the membranes of the _mes'en-ter-y_ to small glands,
which they enter. The first range of glands collects many small
vessels, and transmits a few larger branches to a second range of
glands; and, finally, after passing through several successive ranges
of these glandular bodies, the lacteals, diminished in number and
increased in size, proceed to the enlarged portion of the thoracic
duct, into which they open. They are most numerous in the upper
portion of the small intestine.

253. The THORACIC DUCT commences in the abdomen, by a considerable
dilatation, which is situated in front of the lower portion of the
spinal column. From this point, it passes through the diaphragm, and
ascends to the lower part of the neck. In its ascent, it lies anterior
to the spine, and by the side of the aorta and oesophagus. At the
lower part of the neck, it makes a sudden turn downward and forward,
and terminates by opening into a large vein which passes to the heart.
The thoracic duct is equal in diameter to a goose-quill, and, at its
termination, is provided with a pair of semilunar valves, which
prevent the admission of venous blood into its cylinder.

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251. What is said of the arrangement of the fibres of the muscular
coa