Origin of Muscular Power. 501 



duce heat. He looks upon the whole body as an apparatus work- 

 ing mechanically, and comes to the conclusion that this apparatus 

 can only utilize one-fifth of the whole amount of heat generated 

 in it by oxidation. By multiplying our external work by five, 

 we obtain a minimum of the total amount of actual energy 

 generated by all processes of oxidation during the ascent ; but 

 among these processes there might be some, such as the oxida- 

 tion of the constituents of the circulating blood, which have 

 nothing to do with the production of muscular power. 



Let us therefore content ourselves with the figures whieh we 

 previously obtained, and which will afford sufficient proof for 

 our purpose. We had by their means arrived at the following 

 result: — During our ascent, force-generating processes must 

 have been carried on in our muscles sufficient to afford 751 

 units of heat in Fick's case, and 820 in Wislicenus's. But the 

 actual amount of albumen oxidized could not, as we calculated, 

 have afforded even a third of this quantity of heat. We there- 

 fore repeat, on far more satisfactory grounds, our former conclu- 

 sion, viz. that the oxidation of albuminous substances cannot be 

 the only source of muscular action. We can now go further, 

 and assert that the oxidation of albuminous bodies contributes at 

 the utmost a very small quota to the muscular force. From this 

 assertion it is but a step, which we cannot avoid taking, to the 

 doctrine which has already been frequently proclaimed more 

 or less clearly *, and which has lately been advanced in a most 

 decided manner by Traube, viz. that the substances by the burning 

 of which force is generated in the muscles, are not the albuminous 

 constituents of those tissues, but non-nitrogenous substances, either 

 fats or hydrates of carbon. 



We might express this doctrine by the following simile :— 

 A bundle of muscle-fibres is a kind of machine consisting of 

 albuminous material, just as a steam-engine is made of steel, iron, 

 brass, &c. Now, as in the steam-engme coal is burnt in order 

 to produce force, so in the muscular machine, fats or hydrates 

 of carbon are burnt for the same purpose. And in the same 

 manner as the constructive material of the steam-engine (iron, 

 &c.) is worn away and oxidized, the constructive material of the 

 muscle is worn away, and this wearing away is the source of the 

 nitrogenous constituents of the urine. This theory explains 

 why, during muscular exertion, the excretion of the nitrogenous 

 constituents of urine is little or not at all increased, while that of 

 carbonic acid is enormously augmented; for in a steam-engine, 

 moderately fired and ready for use, the oxidation of iron, &c. 



* For the last three years one of us has in his lectures brought for- 

 ward this doctrine as an hypothesis, but he was not willing to present it 

 to the public until he could bring undeniable facts to prove it. 



Phil. Mag. S. 4. No. 212. Suppl. Vol. 31. 2 L 



