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 sufficient 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 muscular 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. Muscular power, we believe, does not have its immediate origin in oxidation but in the splitting up of an unstable compound into simpler ones.
We differ from him, however, both in regard to the effect of muscular 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 substance 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 physiological exercise of the muscular system increase the elimination of nitrogenized excrementitious principles?"
Were these questions capable of being resolved in this simple manner, 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 interesting 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 simple oxidation of food-constituents. We can not but regret that this fact, which he so clearly appreciates and states, should be supported
