Page:Popular Science Monthly Volume 15.djvu/836

816 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"; but 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 exertion 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 experiments, 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 general 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 criticism 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 Alpine peak of known height, carefully determined the amount of nitrogen 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