CHAPTER V 



AGRICULTURAL CONJURERS 



LIVING bodies are made up largely of 

 oxygen, hydrogen, carbon, and nitrogen. 

 While these are all very abundant in the 

 world, nitrogen seems to be about the most 

 difficult for both animals and the higher plants 

 to get hold of, because in the ordinary form 

 in which it exists in the atmosphere it is not 

 directly available. Man and his relatives, 

 the meat-eating animals, get nitrogen mostly 

 from other animals or from plants, and ul- 

 timately the nitrogen, which animals require, 

 comes from plants. The higher plants get 

 their nitrogen largely from certain chemical 

 compounds in the soil called nitrates, which 

 the bacteria have been active in forming 

 out of the dead stuff of former living things. 

 Give the farmer soil, water, air, sunshine, 



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