to person.

*Conditions Favorable and Unfavorable for Germs.*--Conditions favorable for
germ life are supplied by animal and vegetable matter, moisture, and a
moderate degree of warmth. Hence disease germs may be kept alive in damp
cellars and places of filth. Even living rooms that are poorly lighted or
ventilated may harbor them. Water may, if it contain a small per cent of
organic matter, support such dangerous germs as those of typhoid fever.
Fresh air, sunlight, dryness, cleanliness, and a high temperature, on the
other hand, are destructive of germs. The germs in impure water, as
already noted (page 165), are destroyed by boiling.

*How Germs are Spread.*--Some of the more common methods by which the germs
of disease are spread, and by so doing find new victims, are as follows:

1. _By Means of Foods._--Foods, on account of the locality in which they
are produced or the method of gathering or of handling-them, may become
contaminated with germs, which are then transported with the foods to the
consumer.

2. _By Means of Dust._--Material containing germs, _e.g._, discharges from
the throat and lungs, will on drying form dust. This is lifted with other
fine particles by the air and may be carried quite a distance. The dust
from public halls and other places where people congregate is the kind
most likely to contain disease germs. Dust should be breathed as little as
possible and only through the nostrils. Where one is compelled, as in
sweeping, to breathe dust-laden air for some time, he should inhale
through a moistened sponge, or cloth, tied in front of the nostrils.

3. _By Means of Domestic Pets and Different Kinds of Household
Vermin._--Germs sticking to the bodies of small animals are carried about
and may be easily communicated to people. By this means, rats, mice,
bedbugs, etc., where such exist, are frequently the means of spreading
disease; and particularly dangerous, on this account, is the common house
fly. Feeding as it does on filth of all kinds, it is easy for it to
transfer the bacteria that may stick to its body to the food which is
supplied to the table. The proper screening of houses and the destruction
of material in which flies may develop, such as the refuse from stables,
are necessary precautions.

Germs are spread also by the clothing of people, by railroad and steamship
lines, by the mails, and by the natural elements. In fact, any kind of
carrier, in or upon which germs can live, may s