822 THE POPULAR SCIENCE MONTHLY. 



These facts furnish an important clew to the source of muscular 

 power. The experiments of Yoit and Pettenkof er show that while 

 storing up oxygen during rest the organism is laying up a store of 

 force to be used later ; while those of Henneberg connect this storing 

 up of oxygen with the supply of albuminoids in the food, and render 

 it highly probable that it is accomplished by their means. 



Two hypotheses as to the function of the albuminoids as agents in 

 the production of muscular power at once suggest themselves. The 

 first is, that they simply serve as reservoirs of oxygen, which latter is 

 used at will to burn the non-nitrogenous parts of the food, the result 

 being work, heat, and an increased excretion of carbonic acid and 

 water. This would be the view of those who consider the carbhydrates 

 and fats as the source of muscular power, and its simplicity renders it 

 attractive. It must be noted, however, that it requires us to look upon 

 the non-nitrogenous materials oxidized as part of the muscle, since the 

 latter can perform work independently of the circulation of blood 

 through it. 



A second hypothesis, however, less simple and easily grasped than 

 the first, is considered by many high authorities to accord more closely 

 with the facts of the case and with our general conceptions of vital 

 activity. 



This hypothesis supposes that during rest some of the substances 

 of the muscle-cells decompose into simpler compounds, and in so doing 

 set free their latent energy, which energy, instead of appearing as 

 heat, etc., is used to build up out of other constituents of the cell a 

 still more complex compound containing more potential energy than 

 its components, just as one portion of society may acquire wealth at 

 the expense of another portion, with no increase of the total wealth of 

 the community. 



The substances which are thus "synthesized" are proteine, an un- 

 known non-nitrogenous matter from the blood and oxygen ; the hypo- 

 thetical compound thus formed accumulates to a certain extent in the 

 muscle, and, when the latter is called on to perform work, splits up, 

 yielding carbonic acid, water, and other non-nitrogenous matters, and 

 proteine or some similar compound, and giving forth the amount of 

 force which was required to form it. The non-nitrogenous substances 

 which are formed are supposed to be rapidly excreted ; while the ni- 

 trogenous product, instead of undergoing further decomposition, is 

 used over again to re-form the hypothetical substance. 



This view has much in its favor. Various syntheses like that 

 above outlined are known to take place in the body ; and, moreover, 

 all the facts seem to indicate that muscular force originates in a split- 

 ting up of some substance in the muscle, accompanied by the libera- 

 tion of force, rather than by any process of oxidation in the ordinary 

 sense of the word. 



The hypothesis explains the object of the storing up of oxygen in 



