ply of raw material in
accordance with the needs which his experience has pointed out and with
the teachings of scientific investigators on this subject. Raw material,
however, is not converted into energy by any simple operation. The human
body is made capable of taking raw material of most varied kinds and
transforming it into nutriment capable of being absorbed by the system
and made over into cell tissue. It will be worth while to indicate the
steps of this complex process.

_Digestive processes._

The mouth plays the first part in the scheme of transformation, and here
two operations are performed. First the food is crushed and ground by
the teeth, exactly as when, in some chemical processes, a fine grinding
is essential for the subsequent transformation. In this country, this
preliminary process is often sadly neglected, so much so that a
distinguished investigator, named Horace Fletcher, has, within the last
few years, established a school for the cultivation of the habit of
chewing, with the idea that if this practice could be encouraged and at
least twenty chews taken with every mouthful, the health of the
individual would be vastly improved and sick persons even cured merely
through this practice.

The other function of the mouth is to mix with the food the saliva
which drops from small glands in the back of the mouth into the food.
The action of the saliva is partly to lubricate the food, so that it
will slip down easily, and no better proof of this can be found than
trying to eat a cracker rapidly without chewing. But it also acts on
starch which is not digested easily unless mixed with this ferment. The
action of the saliva on starch is to convert it into sugar, which is
easily absorbed later on. Curiously enough, most persons would be more
apt to chew a piece of meat thoroughly than to chew a piece of bread,
and yet the meat contains practically no starch and therefore does not
need the action of the saliva, whereas bread is chiefly made up of
starch and therefore needs the saliva as an essential for digestion.

The food then passes down into the stomach, which is a sort of
storehouse, preparatory to the really important steps in digestion.
Here, the food is acted upon by another element known as gastric juice,
which is supplied by small glands found in the membrane of the stomach.
The mixture of food and gastric juice is made very thorough by the
continual agitation of the food, so that the mass is so