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Page:Popular Science Monthly Volume 24.djvu/396

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THE POPULAR SCIENCE MONTHLY.

they were enabled to estimate what relation the albuminoid decomposition bore to the amount necessary to supply the power for the ascent. By this method they demonstrated that the whole amount of albuminoid material decomposed during the ascent, even if completely oxidized to carbonic acid, water, and nitrogen (instead of yielding its nitrogen in the form of urea, as is actually the case), would produce less than half the force necessary to raise their bodies through the vertical height to which they ascended. Thus it is shown that the amount of force represented by the actual decomposition of albuminoids during work is by no means adequate to account for the work done, even supposing that all the nitrogenous material decomposed in the body went for that purpose, and that no other muscular work were performed during the ascent than the mere lifting of such a weight to the given height. Both these suppositions are evidently incorrect, as the nitrogen is eliminated in almost equal quantities when no voluntary muscular action is exerted, and the muscular work, voluntary and involuntary (lungs, heart, etc.), on such a trip, would evidently far exceed that necessary for the simple elevation of a dead weight to a specified height.

Experiments conducted by Dr. Parkes on two soldiers proved that a small increase of nitrogen elimination was produced, and also, that this increased elimination of nitrogen may extend for many days after the exercise has ceased.

Dr. Austin Flint, Jr., in an elaborate and thorough investigation on the pedestrian Weston, found a decided increase in the nitrogen eliminated during work; also, a decided increase in the ratio of nitrogen eliminated to that taken in with the food. The value of his results is somewhat impaired for our present purpose, in so far as they relate to the influence of muscular exertion simply, because the condition of the subject during the working period was not such as was favorable for a fair test. His appetite fell off; he slept poorly; was extremely nervous and irritable much of the time; became at times much exhausted and prostrated even to nausea. When the influence of the nervous state and of an exhausted condition on the functions is taken into account, it will be evident that deductions as to the effect of muscular exertion alone would in this instance be open to doubt. Dr. Pavy's experiments on the same pedestrian indicated also an increase in the nitrogen elimination, but only a slight increase as compared with Dr. Flint's results.

What, then, seems tolerably certain is, that muscular exertion increases the nitrogen elimination but slightly, and perhaps only very slightly, so long as the muscular system is moderately exercised and not overtaxed. And, indeed, the pertinent question here would seem to be, "Is the normal muscular action accompanied with any elimination of nitrogen showing a decided relation of the work done to the nitrogen eliminated?" and not "Is the excessive and exhaustive exertion of the muscles accompanied with any increase of nitrogen elimination?"