7 1 i PHYSIOLOGY 



DOG II 



Food Flesh metabolism Condition of dog 



* Grm. 



1500 grm. lean meat . 1522 . . Rest 



1500 1625 .. Work 



1500 1526 .. Rest 



1500 1583 Work 



1500 1535 Rest 



During the work days the animal performed about 1500 kilo- 

 gramme metres in the day. The differences in the protein meta- 

 bolism between the rest and the work days are thus practically 

 insignificant, the nitrogenous output being determined, not by the 

 work done, but by the amount of protein administered in the food. 

 In the second experiment there is an average increase of protein 

 metabolism during the work days amounting to 86 grm. of flesh, 

 a quantity which is insufficient to furnish the energy of the work 

 done. The same results were arrived at in a classical experiment 

 performed by Fick and Wislicenus on themselves, in which they 

 measured their total nitrogenous metabolism during an ascent of 

 the Faulhorn from the Lake of Brienz. The vertical distance tra- 

 versed was 1956 metres. During the seventeen hours before the 

 experiment, the six hours of the ascent, and the seven subsequent 

 hours they ate food practically free from nitrogen. The urine 

 passed during the ascent and during the next seven hours was collected 

 in each case and its nitrogen determined. Fick passed 5-74 grm. of 

 nitrogen, which, if the energy of the protein were totally converted 

 into work, would correspond to 63,378 kilogramme metres. In Wis- 

 licenus the amount was 5-55 grm... of nitrogen, equivalent to 61,280 

 kilogramme metres. Fick, who weighed 66 kilos, in raising himself to a 

 height of 1956 metres, had performed 129,096 kilogramme metres, and 

 Wislicenus, with a weight of 76 kilos, had performed 148,656 kilo- 

 gramme metres. Even if we assume the possibility of a conversion 

 of the total energy of the protein metabolised during the experiment 

 into mechanical energy, we cannot account for more than half of 

 the total work done. All subsequent experimenters have confirmed 

 the deductions which were drawn from these two researches, namely 

 that muscular work, while practically without influence on nitro- 

 genous metabolism, increases enormously the carbonaceous meta- 

 bolism of the body, so that, except in the rare cases where the diet 

 consists of pure protein and the body is practically free from 

 fat, the additional energy output during work is derived from the 

 oxidation of carbon and hydrogen to carbon dioxide and water. 



The general nature of the changes in the metabolism of the body 

 during work is well illustrated by the results obtained by Atwater on 



