ed and may nourish the body is digestion.

2. The work of digestion is chiefly done in the digestive tube or canal,
which is about thirty feet in length.

3. The mouth contains the teeth, and has three pairs of salivary glands
connected with it, which make saliva.

4. The gullet leads from the mouth to the stomach.

5. The stomach is pear-shaped, and holds about three pints.

6. It has an upper and a lower opening, each of which is guarded by a
muscle, which keeps its contents from escaping.

7. The lower opening of the stomach is called the pylorus.

8. The stomach forms the gastric juice.

9. The intestines are about twenty-five feet long. They form the
intestinal juice.

10. The liver lies under the ribs of the right side. It is about half as
large as the head. It makes bile.

11. When not needed for immediate use, the bile is stored up in a sac
called the gall-bladder.

12. The pancreas is a gland which lies just back of the stomach. It
makes pancreatic juice.

13. The spleen is found near the pancreas.

14. There are five important digestive organs--the mouth, the stomach,
the intestines, the liver, and the pancreas.

15. There are five digestive fluids--saliva, gastric juice, intestinal
juice, bile, and pancreatic juice.

CHAPTER VIII.

DIGESTION OF A MOUTHFUL OF BREAD.

~1.~ Let us suppose that we have eaten a mouthful of bread, and can
watch it as it goes through all the different processes of digestion.

~2. Mastication.~--First, we chew or masticate the food with the teeth.
We use the tongue to move the food from one side of the mouth to the
other, and to keep the food between the teeth.

~3. Mouth Digestion.~--While the bread is being chewed, the saliva is
mixed with it and acts upon it. The saliva moistens and softens the food
so that it can be easily swallowed and readily acted upon by the other
digestive juices. You have noticed that if you chew a bit of hard bread
a few minutes it becomes sweet. This is because the saliva changes some
of the starch of the food into sugar.

~4.~ After we have chewed the food, we swallow it, and it passes down
through the oesophagus into the stomach.

~5. Stomach Digestion.~--As soon as the morsel of food enters the
stomach, the gastric juice begins to flow out of the little glands in
which it is formed. This mingles with the food and digests another
portion which the saliva has not acted upon. While this is being done,
the stomach keeps w