imulation of the secretory cells in the stomach are exerted through
the sight, smell, and taste. One often hears the expression: "The food
looked, smelled, or tasted so good that it made my mouth water." This
actually occurs; hence the secretion has been named appetite juice.
This appetite juice acts as a direct stimulant to the cells in the
mucous lining of the stomach, causing a flow of gastric juice. It
cannot be said to cause digestion, but it certainly institutes that
process, thus starting the whole digestional procedure.

~Digestion in the Larger Intestine.~--Science has proved that most of
the nourishing part of the food ingested is digested and absorbed
before it reaches the larger intestine. The two portions of the
alimentary canal known as the small and large intestine are separated
by the ileocecal valve. Cannon claims "that this valve is competent,
that is, under normal conditions the food mass which passes through
into the colon cannot be forced back into the small intestine." The
food mass sometimes contains materials which have escaped digestion,
likewise some of the active enzymes which bring about their
hydrolysis, in which case a certain amount of their digestion may
continue in the large intestine.

So far, investigators have found no enzymes in the fluids secreted by
the cells in the walls of the large intestine, but they have found an
alkaline fluid which assists in completing the digestion of the foods
which has started in other parts of the intestinal tract.

~Absorption.~--Absorption of food occurs in all parts of the
intestinal canal, but the major portion of it occurs in the small
intestines, the mucous membrane lining of which seems particularly
adapted for this purpose. According to Taylor there is no absorption
of fats, carbohydrates, or proteins in the stomach. Other
investigators believe that some of the protein is absorbed and also
some glucose in concentrated solution. However, the stomach cannot be
considered of great value as an absorbing organ. Physiology teaches
that the absorption of the products of digestion occurs by means of
the millions of small projections or villi with which the intestinal
wall is lined. These villi contain numerous capillary blood vessels
and spaces known as lacteals. The former converge into the portal
vein, the latter into the lymphatic vessels and thence into the
thoracic ducts.

~The Absorption of Fat.~--The fats, as has been described, are split
in