586 



GENERAL METABOLISM. 



[CH. XXXIX. 



and Schmidt, use 1*4 N and 6'2 C per kilo, per diem, ^ = 4 '4- 



C 

 In the human being on a flesh diet ^ = 5-2 ; the exchange thus 



approaches the condition of the carnivora. This is illustrated by 

 the following balance-sheet (Ranke) : 



The details of the above experiment may be given as illus- 

 trating the method of working out a problem in exchange of 

 material: 1832 grammes of meat used as food yielded 3-4 per 

 cent, of nitrogen, i.e. 62*3 gr., and 12 '5 per cent, of carbon, i.e. 

 229-3 g r - j 7 g r - f fot added to the food yielded 72 per cent, of 

 carbon, i.e. 50^3 gr. : 229'3 + 5o'3 = 279^6 = total carbon in 

 food. During the same period 86-3 gr. of urea were discharged, 

 containing 46*6 per cent., i.e. 40^4 gr. of nitrogen, and 20 per 

 cent., i.e. 17-3 gr. of carbon, to which must be added 2 gr. of 

 uric acid, containing 33 per cent., i.e. o'66 gr. of nitrogen, and 

 35 per cent., i.e. 0-7 gr. of carbon. Further, 2-9 gr. of nitrogen 

 and 14 gr. of carbon were discharged in the faeces, and 231 gr. 

 of carbon as carbonic acid in the expired air. Hence the total 

 discharge of nitrogen = 40*4 + 0*66 + 2 '9 = 44 gr., and the total 

 discharge of carbon = 17-3 + o' 7 + 14 + 231 = 263 gr. Deducting 

 the quantity of nitrogen discharged from that taken in, 18*3 gr. 

 must have been retained in the body, as 108 gr. of proteid, and 

 consequently 53 per cent, of that weight = 6 2^5 gr. of carbon, 

 were also retained. Comparing the quantity of carbon disposed 

 of in the twenty-four hours with the quantity introduced as food, 

 we find the latter is in excess by 45^9 gr., which must have been 

 derived from the disintegration of the fat of the body. 



Another table of exchange of material on adequate diet may 

 be quoted from the work of Pettenkofer and Voit. This takes 

 into account the elimination of water as well as of carbon and 

 nitrogen. In the first experiment the man did no work. 



