METABOLISM 161 



food. The amount of the nitrogen in the end-products of 

 metabolism present in the faeces of an adult man is estimated 

 at one gram per day. This figure is based on observations 

 made upon the faeces during inanition. 



3. EXAMPLE OF A BALANCE OF NUTRITION 



To illustrate the balance of nutrition we will assume the 

 following case : A man whose body weight at beginning of 

 experiment is 70 kg remains for twenty-four hours in the 

 chamber of Voit's respiratory apparatus. He is fed with 

 meat, bread, butter, potatoes, table-salt, and water. During 

 this time his body weight increases to 70.138 kg. 



i . The amount of food taken up is (in grams) : 



Proteids 130 containing 69 C, 21 N 



Fat 100 " 76 " 



Carbohydrates 400 " 176" 



Salts 30 



Water.. .. 2100 



Total income 2760 containing 321 C, 21 N 



2. The amount of the outgo in urine, faeces, and respira- 

 tion is (in grams): 



Urine 1355 containing 1280 H U O, 24 salts, 12 C, 18 N 



Faeces 120 " 85 " 6 " 18 " 3 " 



Respiration 1867 " 950 '' 250 " 



Total outgo 3342 containing 2315 H a O, 30 salts, 280 C, 21 N 



The person has therefore given off 3342 g, while the income is 

 2760 g. The body weight increased during this time 138 g. 

 Hence some other substance must have been taken in beside the 

 iood, and this is the inhaled oxygen. 



3. The amount of this oxygen can be calculated from the 

 above data according to the following formula : 



Oxygen = (final body weight -+- outgoings) (initial body weight -\- food) 

 = (70138 +3342) -(70000 -M76o)g 



= 720 g. 



4. From the foregoing we can strike the following balance 

 of nutrition (in grams): 



