not allowed to have
any. During the first hour the beer gang did the most work, but after
that the temperance gang did far more work during the entire day. The
next week beer was refused the first gang and given to the second. The
beer helped the second gang do more work than the first one for nearly
two hours, but after that they did much less than the first gang.
This shows that men who wish to do their best work during the entire
day should not use beer.

=Tobacco and the Muscles.=--Many experiments and studies have shown
that the body cannot do its best work when even very small amounts of
poison are taken day after day. The poison in tobacco is believed to
weaken the muscles so much that no man on a football team in any of
our large colleges or universities is allowed to smoke or chew during
the season. Persons training for any contest where much strength is
required do not use tobacco in any form.

=Tobacco prevents Growth of the Muscles.=--The moderate use of tobacco
by men has but little effect on the muscles. It may cause them to tire
a little more easily when doing very hard work. Tobacco poison does,
however, show a marked effect on the muscles of the young.

Very careful measurements made at one of the large universities showed
that the boys who did not smoke grew one tenth more in weight and one
fourth more in height than those using tobacco regularly. This slow
growth in tobacco users is partly due to the fact that tobacco makes
the muscles in the walls of the blood vessels squeeze together so as
to shut off some of the blood from the legs, arms, and other parts, so
that they get too little food. Tobacco may also cause less food to be
digested for the use of the body.

CHAPTER XX

HOW THE BODY IS GOVERNED

=Making the Parts of the Body Work.=--Each of the hundreds of organs
in the body has a certain work to do and this must be done at the
right time. In order that all may work together and each one do its
part when needed, there is a chief manager called the _brain_ and a
helping manager named the _spinal cord_. Millions of tiny threads for
sending messages connect the two managers with every part of the body.
These threads form the _nerves_.

=The Brain.=--The brain is a soft bunch of matter filling the inside
of the skull. The bones of the skull are a quarter of an inch thick
and prevent any common knocks from hurting the brain. It is surrounded
by three coverings which also help shield