824 THE POPULAR SCIENCE MONTHLY. 



and we must content ourselves with two general statements : 1. The 

 heats of combustion of the various food-substances, which serve as the 

 foundation of all such calculations, have not yet been determined 

 with sufficient accuracy to render those calculations demonstrative. 

 2. Even if it were shown that the results of Fick and Wislicenus are 

 correct, and that the albuminoids destroyed during work are not suffi- 

 cient to supply all the force exerted, this in no way invalidates our 

 hypothesis, since the latter does not place the source of muscular 

 power in the albuminoids alone, but in the joint action of these and of 

 non-nitrogenous matters. 



It will be seen that the foregoing views as to the origin of muscu- 

 lar power are in some respects in substantial accordance with those of 

 Professor Flint. Like him we hold that the source of muscular power 

 is to be sought in the muscles themselves, and not in any burning of the 

 constituents of the food in the blood or the juices of the body. Mus- 

 cular power, we believe, does not have its immediate origin in oxida- 

 tion but in the splitting up of an unstable compound into simpler ones. 



We differ from him, however, both in regard to the effect of mus- 

 cular activity upon the destruction of proteine in the body and in 

 regard to the conclusions to be drawn from these effects. Professor 

 Flint claims that work increases the amount of proteine destroyed ; we 

 believe we have shown that neither his own experiments nor those of 

 Dr. Pavy are sufficient to prove this, and that the preponderance of 

 evidence is altogether in the other direction. 



He says further (p. 31) : " In other words, is the muscular sub- 

 stance an apparatus for transforming the force locked up in food into 

 power, or are the muscles themselves consumed, the elements of food 

 being used for their repair? These questions may be resolved by 

 little more than a single experimental line of inquiry : Does physio- 

 logical exercise of the muscular system increase the elimination of 

 nitrogenized excrementitious principles ? " 



Were these questions capable of being resolved in this simple man- 

 ner, their answer would be just the reverse of that which Professor 

 Flint gives to them ; but we have already seen that such researches 

 are entirely inadequate, of themselves, to settle the matter, and that 

 very different considerations must be attended to in order to attain 

 that end. 



Some of these considerations we have endeavored to present, as 

 clearly as might be, in the foregoing pages, while pointing out what 

 seems to us the false method by which Professor Flint, in his very in- 

 teresting book, has sought to maintain a conclusion which itself is 

 doubtless correct, viz., that muscular power originates in vital actions 

 taking place in the cells of the muscles themselves and not in a sim- 

 ple oxidation of food-constituents. We can not but regret that this 

 fact, which he so clearly appreciates and states, should be supported 



