DIETETICS 



403 



In domestic animals the further question of the manurial 

 value of the food has to be considered. The constituents of 

 the excreta which are of special manurial value are the 

 nitrogen and phosphorus. Since so little nitrogen is fixed in 

 the body of the adult animal as proteins, the greater quantity 

 of the nitrogen of the food is recoverable in the urine and 

 fyeces. In ruminants the phosphorus is chiefly excreted in the 

 fseces. 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 : 



BACTERJA 



A MM ON/ A 

 COMPOUNDS 



BACTERIA 



VEGETABLE 

 PROTEIO 



NITRATES 

 OF SOIL 



