nces, and is situated transversely across the posterior wall of
the abdomen, behind the stomach. A duct from this organ opens into the
duodenum.

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254. Describe the liver. 255. What is said of the pancreas?

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256. The SPLEEN, (milt,) so called because the ancients supposed it to
be the seat of melancholy, is an oblong, flattened organ, situated in
the left side, in contact with the diaphragm, stomach, and the
pancreas. It is of a dark, bluish color, and is abundantly supplied
with blood, but has no duct which serves as an outlet for any
secretion. Its use is not well determined.

[Illustration: Fig. 64. The pancreas with its duct, through which the
pancreatic secretion passes into the duodenum.]

257. The OMENTUM (caul) consists of four layers of the serous
membrane, which descends from the stomach and transverse colon. A
quantity of adipose matter is deposited around its vessels, which
ramify through its structure. Its function is twofold in the animal
economy. 1st. It protects the intestines from cold. 2d. It facilitates
the movements of the intestines upon each other during their
vermicular, or worm-like action.

258. Every part of the digestive apparatus is supplied with arteries,
veins, lymphatics, and nervous filaments, from the ganglionic system
of nerves.

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256. Why is the spleen so called? What is peculiar to this organ? 257.
Of what is the omentum composed? What is its use? 258. With what is
every part of the digestive apparatus supplied?

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CHAPTER XIV.

PHYSIOLOGY OF THE DIGESTIVE ORGANS.

259. Substances received into the stomach as food, must necessarily
undergo many changes before they are fitted to form part of the animal
body. The solid portions are reduced to a fluid state, and those parts
that will nourish the body are separated from the waste material.

260. The first preparation of food for admission into the system,
consists in its proper mastication. The lips in front, the cheeks upon
the side, the soft palate, by closing down upon the base of the
tongue, retain the food in the mouth, while it is subjected to the;
process of _mas-ti-ca'tion_, (chewing.) The tongue rolls the mass
around, and keeps it between the teeth, while they divide the food to
a fineness suitable for the stomach.

261. While the food is in process of mastication, there is incorporated
with it