CH. XXXIX.] 



EXCHANGE OF MATERIAL. 



585 



experiments extended over a longer time have shown that sooner 

 or later the body begins to waste if the 15 grammes daily are 

 not supplied in the food. 



In an animal fed exclusively on flesh, the discharge of nitrogen 

 at first increases part passu with the absorption of proteid, the 

 absorption of oxygen being proportionately increased at the same 

 time. The animal, however, gains weight from increase of fat, 

 the proteid being split into what is called a nitrogenous moiety, 

 which is burnt off, and a non-nitrogenous moiety which is converted 

 into fat. 



The discharge of nitrogen is not immediately or markedly 

 influenced by muscular work (see p. 552); the increased com- 

 bustion that occurs in working as compared with resting muscles 

 falls chiefly on their non-nitrogenous constituents. 



Balance of Income and Discharge in Health. 



In Chapter XXVIII. tables are given of adequate diets; these 

 will in our balance-sheets represent the source of income ; the 

 other side of the balance-sheet, the expenditure, consists of the 

 excretions. 



EXCHANGE OF MATERIAL ON AN ADEQUATE DIET 

 (Ranke's table).* 



In man the discharge of nitrogen per kilo, of body-weight 

 is o'2i gramme, and of carbon 3*03 grammes, the quotient 



C 



^ = 14*5. In carnivorous animals, which, according to Bidder 



* The above table was constructed from data derived from the observations 

 of Prof. Ranke on himself. Though made many years ago, Ranke's tables 

 still serve as typical and standard examples of metabolic balance-sheets. 



