388 INFLUENCE OF MUSCULAR EXERCISE ON THE URINE. [BOOK I. 



circulation is much stimulated by muscular exercise, and that respira- 

 tion and the consequent ingestion of oxygen are enlarged by the same 

 means; all of which conditions, apart from the fact of muscular 

 contraction, favour the flow of parenchymatous juices and the manu- 

 facture of urea. He concluded, very justly, that the nitrogenous waste 

 was wholly incompetent to account for the mechanical work done. 

 He believed that the oxygen imported so largely into the body during 

 exercise served to burn up fat in extraordinary quantity and repair 

 the losses of heat which occurred by evaporation and radiation ; and he 

 formed the opinion that the small increase of urea excreted was due to 

 some of the nitrogenous tissues falling a prey to the oxygen during this 

 increased activity of combustion. In short, the increased oxidation of 

 nitrogenous matter was an accident of the general extension of 

 processes of combustion within the body, which would probably have 

 been avoided by a larger ingestion of fats. 



These experiments have been since repeated by Voit 1 with a view to 

 determine not merely the urea, but the total excretion of nitrogen in the 

 urine; and similar experiments have been made by Pettenkofer and 

 Voit 8 on men ; with confirmatory results in each case. 



It must ever be borne in mind, in following the early discussion of the 

 influence of muscular exercise upon the excretion of nitrogen, that the 

 question which divided observers was not whether exercise produces any 

 increase of nitrogenous excretion, but whether it produces an increase 

 corresponding with the mechanical effect of exercise. In respect of the 

 former question, a much greater unanimity would probably be found 

 than is commonly supposed to exist among those who have entered 

 into the discussion. 



Experiments Although Voit selected the lower animals as best 



of Pick and fitted for exact experiment, yet it was by a very simple 

 wisiicenus. observation conducted upon men that the question in one 

 of its phases was finally laid at rest. In the summer of 1865 Professors 

 Fick and Wisiicenus 3 , while abstaining from all nitrogenous food, 

 performed a definite amount of muscular work ; and, having estimated 

 the destruction of albuminous matters in the body from the nitrogen 

 excreted during the same time, they discovered that the combustion 

 of so much albuminous material was quite inadequate to account for 

 the mechanical effect. The work done was an ascent of the Faulhorn 

 to a height of 1956 metres. Therefore the mere mechanical lifting of 

 their bodies through this height was, in the case of 



Fick (wt. 66 kilog.) 129096 kilogm. 



Wisiicenus (wt. 76 kilog.)... 148656 kilogm. 



1 Voit, Zeitsch. filr Biologie, Vol. n. p. 307. 1866. 



2 Pettenkofer u. Voit, Zeitsch. fur Biologie, Vol. n. p. 459. 1866. 



3 Fick und Wisiicenus, Vierteljahresschrift d. naturf. Geselhch. in Zurich, x., 1865. 

 Land., Edin. and Dnb. Phil. Mag,, Ser. 4, Vol. xxxi. p. 485. Suppl. number, 186G. 

 This important paper is also translated in the Ann. des Sci. Nat., S<5r. v. Vol. x., 18G8, 

 p. 257. 





