190 



Influence of Inanition on Metabolism. 



Table 235. Relation of pulse rate, respiration rate, and heat production in 2-day 

 fasting metabolism experiments Continued. 



The differences in total heat production can in only very small part be 

 accounted for by the actual differences in the work of circulation, assuming 

 the accuracy of Loewy & v. Schrotter's 185 estimates of the relative proportion 

 of the total energy output required for circulation, and consequently variations 

 in pulse rate can be taken only as a general index of the fluctuations in the 

 degree of the internal muscular activity including in all probability muscular 

 tonus. 



ENERGY OF THE URINE. 



Fat and carbohydrate katabolized in the ordinary diet are, as a rule, wholly 

 broken down to carbon dioxide and water, and the potential energy they 

 originally contained is completely transformed into heat. A portion of the 

 protein molecule, on the contrary, is not completely oxidized, and is excreted 

 as urea and similar compounds in the urine. The energy of these compounds 

 in the urine must be determined in any series of experiments in which the 

 balance of energy is desired. In order to determine the potential energy of 

 urine, it is necessary to burn the dry matter in a calorimetric bomb and 

 measure the heat actually given off. The technique of the determination of 

 the heat of combustion of urine has received special consideration in an earlier 

 paragraph (see p. 16). The errors involved, in all probability render the 

 determinations somewhat too low rather than too high, although the method 

 used in these investigations has given the highest heat of combustion of any 

 method with which we are familiar. In fasting urine we have reason to 

 suppose not only that portions of the protein katabolized are excreted unoxi- 



100 Loc. cit. 



