"_Other Uses of the Digestive Fluids._--In addition to the uses which we
have already stated, several of the digestive fluids possess other
interesting properties. The saliva aids the stomach by stimulating its
glands to make gastric juice. The gastric juice and the bile are
excellent antiseptics, by which the food is preserved from fermentation
while undergoing digestion. The bile also stimulates the movements of
the intestines by which the food is moved along, and aids absorption. It
is remarkable and interesting that a fluid so useful as the bile should
be at the same time composed of waste matters which are being removed
from the body. This is an illustration of the wonderful economy shown by
nature in her operations.

"The food is moved along the alimentary canal, from the stomach
downward, by successive contractions of the muscular walls of the
intestines, known as peristaltic movements, which occur with great
regularity during digestion.

"_Absorption_.--The absorption of the food begins as soon as any portion
has been digested. Even in the mouth and the esophagus a small amount is
absorbed. The entire mucous membrane lining the digestive canal is
furnished with a rich supply of blood-vessels, by which the greater part
of the digestive food is absorbed.

"_Liver Digestion._--The liver as well as the stomach is a digestive
organ, and in a double sense. It not only secretes a digestive fluid,
the bile, but it acts upon the food brought to it by the portal vein,
and regulates the supply of digested food to the general system. It
converts a large share of the grape-sugar and partially digested starch
brought to it into a kind of liver starch, termed glycogen, which it