816 THE POPULAR SCIENCE MONTHLY. 



of Lehmann (p. 35), and states (p. 41) that "the change of the normal 

 diet to a regimen of non-nitrogenous matters alone of itself diminishes 

 very largely the excretion of nitrogen " ; hut the more recent results 

 of Voit and others are passed over in silence, though on pages 26-28 

 he mentions some facts and introduces some considerations which go 

 to show the correctness of these results. 



Coming now to the main question, we follow the general order of 

 Professor Flint's book, and consider, first, the effect of muscular exer- 

 tion upon the metamorphosis of matter in the body as shown by the 

 excretions, and, second, the conclusions which can be drawn from 

 these effects as to the proximate source of muscular power. 



According to Professor Flint (p. 40), the experiments of Fick and 

 Wislicenus in 1866 constituted " the starting-point of the new theory 

 of the origin of muscular power." This, however, can hardly be said 

 to be the case, at least as regards the experimental evidence on which 

 that theory is based. We have already stated that Voit was the first 

 to seek for evidence of the truth of the views held by his predecessors, 

 and his experiments, as also those of E. Smith, antedate those of Fick 

 and Wislicenus by some six years. Not only so, but the theory itself 

 had been broached before Fick and Wislicenus made their experi- 

 ments, as may be seen from their paper on the subject. At the same 

 time their results gave it a powerful impulse and won for it more gen- 

 eral attention. 



Voit's conclusions have been fully corroborated by numerous and 

 able investigators,* and are at present accepted by the great majority 

 of physiologists ; and we naturally expect some reference to them in a 

 critical discussion of this question. We find, however, no mention of 

 them ; we are left to infer that the experiments of Fick and Wislicenus 

 are the chief basis for the conclusion that work does not increase the 

 elimination of nitrogen in the urine, and the author enters into a criti- 

 cism of these experiments which is groundless, since it mistakes entirely 

 their object. 



The experiments of Fick and Wislicenus were not designed to show 

 that work did not increase the destruction of proteine in the organism, 

 but that the latent energy of the amount destroyed was insufficient to 

 account for the work done. For this purpose they ascended an Al- 

 pine peak of known height, carefully determined the amount of nitro- 

 gen excreted during the ascent, and calculated from this the amount 

 of proteine destroyed. Their diet before and during the performance 

 of the work contained no proteine. On reckoning the amount of latent 

 energy contained in the proteine destroyed, as shown by the quantity 

 of heat which it would have yielded if burned, they found this energy 



* Among these confirmatory results may be mentioned, as having historical as well as 

 scientific interest, those obtained in 1867 by T. R. Noyes, M. D. ("American Journal of 

 Medical Science," October, 1867), then a student in the Yale Medical School, which in the 

 main agreed with those of Voit. 



