When used in large quantities, it injures nearly all of the
tissues, and when taken habitually, even in small doses, it leads to the
formation of the alcohol habit which is now recognized and treated as a
disease. This and other facts show that alcohol is not adapted to the body
plan of taking on and using new material (Chapter XI), and no substance
lacking in this respect can properly be classed as a food.(56) Instead of
classing alcohol as a food, it should be placed in that long list of
substances which are introduced into the body for special purposes and
which are known by the general name of

*Drugs.*--Drugs act strongly upon the body and tend to bring about unusual
and unnatural results. Their use should in no way be confused with that of
foods. If taken in health, they tend to disturb the physiological balance
of the body by unduly increasing or diminishing the action of the
different organs. In disease where this balance is already disturbed, they
may be administered for their counteractive effects, but always under the
advice and direction of a physician. Knowing the nature of the disturbance
which the drug produces, the physician can administer it to advantage,
should the body be out of physiological balance, or diseased. Not only are
drugs of no value in health, but their use is liable to do much harm.

NATURE OF DIGESTION

Before the nutrients can be oxidized at the cells, or built into the
protoplasm, they undergo a number of changes. These are necessary for
their entrance into the body, for their distribution by the blood and the
lymph, and for the purposes which they finally serve. The first of these
changes is preparatory to the entrance of the nutrients and is known as
_digestion_. The organs which bring about this change, called digestive
organs, have a special construction which adapts them to their work. It
will assist materially in understanding these organs if we first learn
something of the nature of the work which they have to perform.

*How the Nutrients get into the Body.*--The nature of digestion is
determined by the conditions affecting the entrance of nutrients into the
body. Food in the stomach and air in the lungs, although surrounded by the
body, are still outside of what is called the _body proper_. To gain
entrance into the body proper, a substance must pass through the body
wall. This consists of the skin on the outside and of the mucous linings
of the air passages and other t