PLANTS WITHOUT SEEDS 
*9 
teria do when they get into our bodies. Once 
they are in, they grow and multiply, and of 
course the more of them there are, the more 
poison they make. Sometimes our bodies are 
strong enough to resist this poison and throw it 
off. At other times it is too strong and makes 
us sick. Of course the best way to prevent sick¬ 
ness is to keep the bacteria out. They come in 
chiefly through our mouths, noses, and cuts in 
the skin. They cannot stand heat. We can 
kill them by boiling food, and by washing 
articles that may carry bacteria in boiling water. 
This is called sterilizing. Diphtheria, tubercu¬ 
losis, and influenza are three common diseases 
brought by bacteria. 
The farmer is fighting bacteria all the time. 
They cause diseases of plants as well as of ani¬ 
mals and people. They get through the skins 
of fruit and vegetables that have been cut or 
bruised and cause them to spoil. They spoil 
meat. They produce bad odors, and are the 
cause of most of the smells around the barn. 
The farmer’s best weapon in fighting them is 
