sickness in our
land is catching sickness. That is, it is sickness which passes from
one person to another and is caused by tiny germs or microbes. A
catching sickness is called a _contagious disease_. Some of the common
catching diseases are sore throat, colds, diphtheria, pneumonia,
typhoid fever, measles, grippe, and whooping cough.

=How we get a Catching Sickness.=--We get a catching sickness by
taking into our bodies the germs from some other person. The germs of
the sick do not pass off in the breath, but in the spit or anything
else which comes from their bodies. This is why the spit and all slops
from the sick room should be burned, buried, or destroyed in some way.

[Illustration: FIG. 94.--How the germs of disease start on their
mission of death. This sewer carries slops from the houses of the sick
and well and empties into a stream used below for drinking water.]

We should think it very wicked if a showman should turn his lions and
tigers loose in a crowd of women and children. Somebody would surely
be killed and others hurt. It is just as wrong to turn loose the
germs of the sick by throwing the spit and the slops where they will
get into a stream or where the flies may find them and by soiling
their feet leave death in their trail wherever they crawl.

=How the Germs of Sickness catch Us.=--The germs of sickness have no
feet to walk and no wings to fly, yet they easily travel from the sick
to the well. They are not killed by being frozen, or drowned by
floating in water, or destroyed by drying. For this reason they can
travel with the ice, water, milk, and dust.

In Buffalo, New York, fifty-seven children caught the scarlet fever in
one week by using milk cared for by a boy who was getting well from
the scarlet fever.

The germs of sickness are so small that a million can hang to the
hands or clothing and not be seen. For this reason they are often left
clinging to the fingers, desks, books, and pencils, and travel in
large numbers on the feet of flies. The surest way the germs have of
getting from one person to another is by the common drinking cup.

[Illustration: FIG. 95.--Photograph of clear beef broth jelly in which
a fly walked five minutes scattering germs. Two days later each germ
brushed off the fly's feet grew into a city of germs appearing as a
white spot.]

=The Common Drinking Cup is an Exchange Station for Germs.=--The most
careful examinations have shown that there are thousands of