120 RESPIRATORY EXCHANGE OF ANIMALS AND MAN 



increased oxidative energy of the muscle cell must be assumed. Re- 

 cent observations by Lindhard [1915] confirm this result. 



3. The influence of feeding and fasting. Magnus-Levy [1894] 

 found that the standard metabolism, measured 12-24 hours after the 

 last meal, became higher when the animal (dog) had been fed for some 

 time on protein. Schreuer[i9O5] has shown, however, that the influence 

 disappears in the next 24 hours and that we have to do in this case with 

 a direct effect of food, which has not been completely catabolized or 

 excreted in the usual period, and not with any increase in the oxidative 

 energy of the cells. 



E. Voit [1901] found that the 24-hour metabolism of fasting warm- 

 blooded animals (man, dogs, rabbits, hens) fell off steadily during a 

 prolonged fast when it was calculated per unit of the surface as deter- 

 mined by the formula s = k w% y and also when calculated per kg. of 

 the weight. Voit figured out by a somewhat complicated calculation 

 the amount of "nitrogen in active organs," one might perhaps say of 

 " protoplasm " in his fasting animals, and found that after an initial fall 

 the metabolism per unit of active nitrogen remained practically con- 

 stant throughout the fast. 



I reproduce one of his Tables calculated from an experiment by 

 Rubner (Table XXIX). 



TABLE XXIX. FASTING METABOLISM OF A DOG. 



It must be remembered that in these experiments standard condi- 

 tions were not maintained, and that the animals in all probability made 

 more muscular movements during the first days of the fast than later. 

 It has been shown on man, notably by Zuntz and his collaborators 



