FUNGI 



CHAPTER IV. 



SOME PLANTS THAT DO NOT MAKE THEIR OWN LIVING. 



The world is full of vagabond plants, and the smallest 

 ones make the most trouble. Many of these plants belong 

 to the group bacteria; they are also commonly called 

 microbes or germs. They are very small indeed, so minute 

 that it takes skillful hands and the best of microscopes to 

 find out about them. But they are everywhere, in the air, 

 in the soil, in water and in the tissues of plants and ani- 

 mals. Like all other plants considered in this chapter, 

 bacteria have no chlorophyll, and so they must live on 

 other plants and animals, living or dead. When these 

 little plants have warmth and moisture and just the right 

 sort of food, they grow and multiply at a most astonishing 

 rate; many millions of plants can arise from one, in a single 

 day. When they cannot get food, they simply rest and 

 wait. Some kinds can remain dormant for years, and they 

 are so minute that they can be scattered far and wide in 

 this condition. 



In order to get their food, bacteria must break up or- 

 ganic substances and cause many changes. Some that live 

 in the blood of animals cause serious diseases. Often a 

 knowledge of the habits of these tiny plants helps us to get 

 rid of them. It is known, for instance, that a few hours of 

 sunlight and dry air will kill the bacteria that cause con- 

 sumption, and that boiling temperature kills many danger- 



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