MUSCLE. 267 



behavior of the nitrogenized constituents of the muscle at rest 

 and during activity, by determining the total quantity of nitrogen 

 eliminated under these different conditions of the body. While 

 we in the past agreed with the views of LIEBIG that the elimination 

 of nitrogen by the urine was increased by muscular work, the 

 researches of several experimenters, especially those of VOIT on 

 dogs and VOIT and PETTENKOFER on man, have led to quite differ- 

 ent results. They have shown that during work no increase or only 

 a very insignificant increase in the elimination of nitrogen takes place. 

 We must not conceal the fact that we have a series of experiments 

 which show a significant increase in the exchange of proteids during 

 or after work. We have as example the observations of FLINT * 

 and PAVY on a pedestrian, v. WOLFF, v. FUNKE, KRETJZHAGE 

 and KELLNER on a horse, and lately those of ARGUTINSKY on him- 

 self, which show an undoubted increase in the elimination of 

 nitrogen during or after work. 



The elimination of nitrogen is mainly dependent upon causes 

 which will be spoken of later (Chapter XV), such as the quantity 

 and composition of the food, the condition of the adipose tissue, 

 the action of work on the respiratory mechanism, etc., etc., all of 

 which can hardly have received sufficient consideration in the last- 

 mentioned experiments. The strong proof which the very careful 

 experiments of VOIT and of PETTENKOFER and VOIT furnish in 

 support of this theory is hardly destroyed by these investigations; 

 though we must admit that this question is still somewhat unsettled. 

 Even if we consider that muscular work does not cause any 

 increase in the elimination of nitrogen, which has been quite posi- 

 tively proved, still we do not exclude the possibility of an increased 

 exchange of proteids in the muscle. It is possible on account of 

 the functional exchange action of the organs, of which RANKE has 

 made a special study, that an increased exchange of proteid in the 

 muscles may be compensated by a simultaneous decreased exchange 



1 The results obtained by Prof. A. FLINT were derived from experi- 

 ments made upon the pedestrian WESTON, who in 1870, in the American Insti- 

 tute Building (New York), travelled a distance of 317 miles in five days. 

 The chemical part of the work was performed under the immediate supervision 

 of Prof. R. O. DOREMUS. For fifteen days, five before, five during, and five 

 after the walk, all ingesta and excreta were weighed or measured and analyzed. 

 The experiments of Dr. PAVY were made in London in 1876. TRANSLATOB. 



