CHAPTER III 

 BACTERIA 



WHAT THEY ARE 



THEY are vegetables. They are the smallest 

 of all plants. Twenty-five thousand bacteria end 

 to end would cover a distance of I inch. They 

 are so small that it takes a powerful magnifying 

 glass to see them. They have no roots and no 

 leaves. Some of them are shaped like cucumbers, 

 and others like oranges. 



Most large plants, such as trees and corn and 

 wheat, are harmless. A few are poisonous, such 

 as poison ivy, mushrooms and sumach. Among 

 bacteria there are hundreds of kinds entirely 

 harmless, but a few are poisonous, such as typhoid, 

 tuberculosis, sore throat and diphtheria. The 

 poisonous bacteria have learned to grow in the 

 warm and moist climate of human and animal 

 bodies. There they make poisons which cause 

 diseases known by their names. 



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