How can we 
guard against 
them? 
68 WORLD OF INVISIBLE LIFE 
In diphtheria, for instance, the germs in the 
throat may be blown into the air by the person’s 
breathing or coughing, or they may be left by' 
the lips on a drinking cup. In tuberculosis, 
matter from the lungs passes into the mouth 
and then into the air by coughing and sneezing. 
In typhoid fever the germs leave the body 
through the bowels and thus get into the 
sewage, and from there sometimes into the 
water supply. So one can get typhoid fever 
from impure drinking water, and diphtheria 
from using a drinking cup that someone with 
diphtheria has recently used. By breathing air 
into which someone with diphtheria or tuber¬ 
culosis has recently coughed, one can get either 
disease, without ever coming into touch with 
the person who is sick. But germs in the air 
live the shortest time of all, so that danger 
from this source is very slight, unless one is 
in the same room with the sick person. But 
it is necessary that people should always be on 
their guard against these deadly germs. 
There is another means by which some 
