392 NUTRITION. 



Products of Disassimilation. 



Name of principle. How excreted. 



f Principally by the 



lungs ; but also 



Carbonic acid (C0 2 ) ................................ < by the skin, and 



in solution in the 

 [ excreted fluids. 

 Alkaline sudorates (Sudoric acid, CioH 8 O i3 N) ........... Perspiration. 



f Principally in the 



urea(c 2 H 4 N 2 o 2 ).. . 



tain quantity in 

 I the perspiration. 

 Urate of soda (Uric acid, C 6 HIS T 2 2 +HO) ................. Urine. 



Urate of ammonia 



Urate of potassa 



Urate of lime 



Urate of magnesia 



Hippurate of soda (Hippuric acid, Ci 8 H 8 N0 6 ) 



Hippurate of potassa 



Hippurate of lime 



Creatine (C 8 H 9 4 N 3 + 2HO) ............................ " 



Creatinine (C 8 H 7 2 N 3 ) ................................. " 



Oxalate of lime (CaO,C 2 3 +2HO) ....................... " 



Xanthine (C 10 H 6 N 4 4 ) ................................. " 



Stercorine (changed from Cholesterine, C 25 II 22 0, of bile). . . Faeces. 

 Excretine (C 78 H 78 2 S) ................................. " 



In the above list we have omitted all doubtful excremen- 

 titious principles, as well as the inorganic compounds found 

 in the excreted fluids ; and we can safely assume that the 

 substances therein enumerated represent, as far as we are 

 now able to determine, the physiological wear of the organ- 

 ism. We shall not again discuss the fact that the life of 

 tissues involves physiological waste or decay, and that the 

 excrementitious principles proper represent the final changes 

 of the organic substance. We know that this process goes 

 on without necessarily involving exercise of the peculiar 

 functions of the parts ; but it is no less true that exercise, 

 or work, increases the activity both of nutrition and wear. 

 This is one of the great principles underlying all our ideas 



