Chap. IX.] 



NUTRITION AND METABOLISM. 



193 



of the ultimate products of waste. The katastatic surplus marks 

 the energetic capital with which the animal is credited. In a 

 complete life-pyramid, however, this will not be so ; for the 

 lower anastatic stages by which the food is raised to its high 

 level of energy and complexity falls within the life-work of the 

 plant. The accompanying figure (58) will roughly symbolise 

 this conception, the notch between plant protoplasm and animal 

 protoplasm being intended to convey the fact that in the animal 

 the food prepared by the plant is partly broken down into lower 

 products before it is finally built up into higher. 



The following nitrogenous substances are among those found 

 in animal tissue. They are arranged in order of chemical 

 degradation : 



Cerebrin, 



Tyrosin, 



Hippuric Acid, 



Leucin, 



Guanin, 



Hypoxanthin, 



Kreatin, 



Kreatinin, 



Xanthin, 



Uric Acid, 



Allantoin, 



Urea, 



C 9 H 9 NO.. 

 C 6 H 13 N0 2 . 

 C 6 H 6 N 6 0. 

 C 6 H 4 N 4 0. 



c 4 H 9 N 3 o 2 . 



C 4 H 7 N S 0. 



C 6 H 4 N 4 2 . 

 C 6 H 4 N 4 3 . 

 C 4 H 6 N 4 3 . 

 CH 4 N 2 0. 



13 



