r a headache is a danger signal. It tells
that the food organs are not doing their work as they should and unless
help is given sickness is likely to occur. Medicine may help, but using
foods easy to digest, eating less, chewing more, and getting plenty of
exercise in the fresh air are likely to be the greatest aids to health.

=The Chewing of Tobacco and Digestion.=--Some men chew tobacco as much
as ten hours every day. The taste of the tobacco makes the saliva flow
from the glands into the mouth. This dissolves the poison out of the
tobacco and it is then spit out. If the tobacco-soaked saliva were all
swallowed, the man would be poisoned.

The chewing of tobacco causes the loss of much saliva which is needed
to help digest the food. Anyone who tires his jaw by chewing tobacco
is not likely to chew his food well. Some of the poison in the tobacco
is taken into the body through the blood vessels in the lining of the
mouth. This is shown by the fact that a boy not used to tobacco
becomes very sick after he has chewed a mouthful for only ten minutes.

=Smoking and Digestion.=--Some persons think that the smoking of a
cigar after a meal helps digestion. It may do so in some cases. If a
lawyer is much excited about a case he is trying, or a business man is
in trouble about his losses, the thinking causes the blood to flow to
the head when it is needed in the stomach to give out digestive juices.

The taste of the tobacco smoke may cause some gastric juice to run out
into the stomach, but at the same time it is likely to hurt the nerves
of taste so that food cannot give so much enjoyment as when the nerves
are unharmed. Although smoking may at the time help digestion a
little, the poison in the tobacco may afterward injure the body. This
poison is especially harmful to growing bodies, and boys who are wise
will refuse to smoke on all occasions.

=Beer and Digestion.=--Some people drink beer with their meals because
they think it makes the food taste better. It really prevents them
from getting the full taste of the food because they wash it down
before it is well soaked with the saliva.

[Illustration: FIG. 29.--The stomach, showing the arrangement of the
muscular fibers which alcohol may hinder from doing good work. At the
right a piece is cut out of the top layer of muscle.]

The flavor of beer may sometimes cause an extra flow of gastric juice
into the stomach, but the alcohol in the beer is likely to make the
mov