SIGNIFICANCE OF GAS EXCHANGE 



in the urine, 1 are subtracted from the measured respiratory exchange. 

 The respiratory quotient for the remaining " non-protein " gas exchange 

 is thereupon formed, and can be utilized for a quantitative computation 

 of the distribution of the metabolism on fat and carbohydrate. Zuntz 

 and Schumburg [1901] have compiled the following table, showing the 

 distribution directly from the non-protein respiratory quotient : 



TABLE I. 



I give as an example the calculation of one 8-hour period from 

 a series of determinations made on two Eskimo subjects by A. and 

 M. Krogh. They found 



Nitrogen in urine gr. 34*93 corresponding to a respiratory ex- 

 change of 34-93 x 5-923 = 206-9 litres oxygen and 34-93 x 4754 = 

 1 66-0 litres CO 2 



The total gas exchange during the period was 405 lit. O a and 331 lit. CO 2 

 The protein metabolism corresponded to 206-9 ,, 166 ,, 



The non-protein metabolism therefore to 198-1 165 



The respiratory quotient of the non-protein metabolism was 

 T"b1rr = '^33- By interpolation in Table I we find that this corre- 

 sponds to 0*510 gr. glycogen and 0*293 gr. fat per litre oxygen. The 

 quantities of the different foodstuffs actually Catabolized by both sub- 

 jects during the period have been therefore 



Protein . 

 Glycogen 

 Fat 



34-93 x 16 = 218 gr. 

 198-1 x 0-510 = 99 

 198-1 x 0-293 = S 8 



Calculations such as these rest upon the assumption that no sub- 

 stances are catabolized except carbohydrates, fats and proteins, and 

 further that no syntheses of these substances or others take place. 



1 This computation is valid only for man and for those mammals in which urea is the 

 chief product ot the protein catabolism. 



