flow. Saliva is secreted only one fourth as fast when eating oatmeal and milk as when eating dry toast (Fig. 94).
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Fig. 94.—Cells of a Salivary Gland
A, after rest, full of granules; B, after short activity; C, after prolonged activity, cells shriveled and granules lost.
Starchy grains and fruits were eaten by early man without cooking,
and required more chewing than sweet, ripe fruits or oils or proteids.
Hence the saliva was given the power of acting upon the starch, for
it must remain in the mouth longer. The saliva is alkaline; and if
the food is not thoroughly mixed with it, the stomach digestion will
also be imperfect, for the alkaline saliva is necessary to excite an abundant flow of gastric juice in the stomach (Exp. 1).
Eating slowly is difficult because of the grinding and cooking of food; hence the common practice of overeating. To eat slowly (1) do not take large mouthfuls; (2) do not take a second morsel until the first has been swallowed; (3) sit erect or lean back after putting food into the mouth; (4) the hands should lie idle most of the time. To lean forward and keep food traveling to the mouth like coal into a chute means overeating with all its bad effects.
Chewing gum is a coarse and impolite habit, and wastes the saliva, besides weakening the glands and irritating the stomach by the saliva that is continually swallowed. Chewing tobacco has several of these disadvantages, besides allowing the poison in the tobacco to be absorbed by the mucous lining of the mouth.
The pharynx (far'inks), or throat, is a muscular bag suspended
behind the nose and mouth. (See Fig. 89, also
Fig. 83.) There are seven openings into the pharynx: two
from the nostrils, two from the ears, one each from the
mouth, larynx, and gullet. Which of these openings are
downward? Forward? Lateral?
The gullet (or esophagus) is a muscular tube about nine
