) 14, The pancreas. 15, 15, 15, 15, The small
intestine. 16, The opening of the small intestine into the large
intestine. 17, 18, 19, 20, The large intestine. 21, The spleen. 22, The
upper part of the spinal column.]

CHAPTER XV.

HYGIENE OF THE DIGESTIVE ORGANS.

273. It is a law of the system, that each organ is excited to healthy
and efficient action, when influenced by its appropriate stimulus.
Accordingly, nutrient food, that is adapted to the wants of the
system, imparts a healthy stimulation to the salivary glands during
the process of mastication. The food that is well masticated, and has
blended with it a proper amount of saliva, will induce a healthy
action in the stomach. Well-prepared chyme is the natural stimulus of
the duodenum, liver, and pancreas; pure chyle is the appropriate
excitant of the lacteal vessels.

274. The perfection of the digestive process, as well as the health of
the general system, requires the observance of certain conditions.
These will be considered under four heads:--1st. The _Quantity_ of
food that should be taken. 2d. Its _Quality_. 3d. The _Manner_ in
which it should be taken. 4th. The _Condition_ of the system when food
is taken.

275. The QUANTITY of food necessary for the system varies. Age,
occupation, temperament, temperature, habits, amount of clothing,
health and disease are among the circumstances which produce the
variation.

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273-330. _Give the hygiene of the digestive organs._ 273. Give a law
of the system. What is the appropriate stimulus of the salivary glands
during mastication? Of the stomach? Of the duodenum? Of the lacteal
vessels? 274. What does the perfection of the digestive organs
require? 275. What exert an influence on the quantity of food
necessary for the system?

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276. _The child and youth require food to promote the growth of the
different parts of the body._ The more rapid the growth of the child,
the greater the demand for food. This accounts for the keen appetite
and vigorous digestion in childhood. When the youth has attained his
full growth, this necessity for nutriment ceases; after this period of
life, if the same amount of food is taken, and there is no increase of
labor or exertion, the digestive apparatus will become diseased, and
the vigor of the whole system diminished.

_Observation._ When the body has become emaciated from want of
nutriment, either from famine or