66 
WORLD OF INVISIBLE LIFE 
How do they 
enter our 
bodies? 
Blood poisoning 
microbes 
way into the body is also important. Often 
the body can fight a small number of disease- 
germs, but the entrance of a large number will 
cause illness. 
Germs get into the body in many ways, and 
each germ may have its own favorite way of 
entering. Some kinds of germs can get in only 
one way, and if they enter in other ways, they 
cause no harm. But some of them, like the 
tuberculosis germ, cause trouble no matter how 
they get into the body. 
Some germs get in chiefly through the skin; 
among them are those that cause little sores or 
boils. These germs, however, are harmless in 
the stomach. The germ of lockjaw can cause 
illness only when it enters through the skin. 
Usually, if the skin is unbroken, a person is 
almost perfectly protected against the entrance 
of the kinds of germs that pass through the 
skin. But any tiny cut or bruise or skinned 
place will allow them to get in and cause an 
infection; sometimes even blood-poisoning re¬ 
sults, causing death or serious injury. 
Scratches from pets may 
cause serious illness 
