digestion, may be here summarized: They supply the necessary force for
masticating the food. They propel the food through the canal. They mix the
food with the different juices. At certain places they partly or
completely close the passage until a digestive process is completed. They
may even cause a reverse movement of the food, as in vomiting. All of the
alimentary muscles, except those around the mouth, are involuntary. Their
work is of the greatest importance.

*Other Purposes of the Digestive Organs.*—The digestive organs serve other
important purposes besides that of dissolving the foods. They provide
favorable conditions for passing the dissolved material into the blood.
They dispose of such portions of the foods as fail, in the digestive
processes, to be reduced to a liquid state. A considerable amount of waste
material is also separated from the blood by the glands of digestion
(especially the liver), and this is passed from the body with the
undigested portions of food. Then the food canal (stomach in particular)
is a means of holding, or storing, food which is awaiting the processes of
digestion. Considering the number of these purposes, the digestive organs
are remarkably simple, both in structure and in method of operation.



HYGIENE OF DIGESTION


Many of the ills to which flesh is heir are due to improper methods of
taking food and are cured by observing the simple rules of eating. Habit
plays a large part in the process and children should, for this reason, be
taught early to eat properly. Since the majority of the digestive
processes are involuntary and the food, after being swallowed, is