FEEDING OF ANIMALS. 341 



Royal Society on December 16, 1858. 1 He records the Muscular 

 quantities of carbonic acid exhaled in grains per minute, and Sj^Lrf- 

 these we have calculated into grams per hour, and so give ation of 

 them below :— a a ^ 



Carbonic acid, 

 grams per hour. 



19.2 



23.0 



38.1 



70.4 



100.4 



189.2 



During light sleep 



Lying down, scarcely awake 



Sitting quietly . 



Walking two miles per hour 



Walking three miles per hour 



On treadwheel, ascending 28.65 feet per minute 



There was, therefore, very greatly increased exhalation of 

 carbonic acid with increased muscular exercise. 



Dr E. Smith also conducted experiments on the amounts Labour 

 of urea eliminated under different conditions, both as to food ^??f' 

 and exercise. The investigation was commenced in January 

 1860, and continued up to March 1862, a period of two years 

 and two months. These results were also published in a 

 paper in the Philosophical Transactions of the Eoyal Society. 2 

 The general result was, that there was great variation in the 

 amount of urea passed when there was concurrent variation 

 in the amount of nitrogenous substance in the food ; but, on 

 the other hand, comparatively little variation in the amount 

 of urea voided, with great variation in the amount of labour 

 performed. 



Thus, then, Dr Smith's results, both those showing the Confirming 

 amounts of carbonic acid exhaled, and those relating to the f°J£^ 0S 

 amounts of urea voided, fully confirmed the view that with 

 muscular exertion there was marked increase in the demand 

 for the non-nitrogenous, and but little if any in that for the 

 nitrogenous, constituents of food. 



Experiments made by Bischoff and Voit in 1858 and Voifsex- 

 1859 3 with a dog, either submitted to hunger, or fed from P^^nents. 

 time to time on foods containing very different amounts of 

 nitrogenous substance, showed very variable amounts of urea 

 voided, although the animal was kept under equal conditions 

 as to exercise. Still, on the publication of their results in 

 1860, the authors assumed, that although there had been no Voit's 

 greater exercise of force manifested in the form of external views - 

 work, yet when the amount of nitrogenous substance in the 

 food was greater, and the amount of urea voided correspond- 

 ingly greater, there must have been a corresponding increase 

 in the force exercised in the conduct of the actions within the 



1 Phil. Trans., 1859, vol. 149, pp. 681-742. 



2 Phil. Trans., 1861, vol. 151, pp. 747-834. 



3 Die Gesetze der Ernahrung dcs Fleischfressers, 1860. 



