FOOD REQUIREMENTS 



381 



the faeces. Hence, by careful storage of the excreta and its 

 proper disposal, a large return to the land may be made. 

 This cycle between animal and plant may be illustrated by 



the following diagram 



ANIMAL 

 P ROT El a 



BACTERIA 



A MM ON/ A 

 COMPOUNDS 



BACTERIA 



VEGETABLE 

 PROTEJO 



NJTRATIS 

 OF SOIL 



Fig. 161. — Diagram to illustrate Nitrogen Cycle. 



