502 On the Origin of Muscular Power. 



would go on tolerably equably, and would not be much increased 

 by the more rapid firing necessary for working, but much more 

 coal would be burnt when it was at work than when it was 

 standing idle. We therefore conclude that since the burning 

 of albumen cannot be the only source of muscular power, it is 

 not in any way concerned in its production ; and to this conclu- 

 sion we are impelled by the consideration that in so delicate an 

 apparatus as a muscle-fibre must be, it is not likely that different 

 kinds of chemical processes should be employed to produce the 

 same effect. Even steam-engines are not indifferent as to the 

 material burnt in them; in one made to burn wood, it would 

 not do to use coal. How, then, is it possible to conceive that 

 the muscle-machine was constructed especially for albumen, 

 and that when enough albumen is not to be had, it puts up con- 

 tentedly with non-nitrogenous fuel ? That it does make use of 

 non-nitrogenous material, we have by our experiment proved 

 beyond a doubt. We therefore conclude that since the muscle- 

 machine can undoubtedly be heated by means of the non-nitroge- 

 nous fuel, this fuel is in all cases that best suited for it. 



In conclusion we may be permitted to return to the more 

 general considerations touched upon in the opening of our paper. 

 By the light of our hypothesis, the great efforts for the diges- 

 tion of the hydrates of carbon which we meet with in the animal 

 world are perfectly intelligible. We see, for instance, among 

 the ruminants, most complicated apparatus, constructed for the 

 purpose of saccharifying at least a little of the cellulose, hard as 

 it is to dissolve, and of thus gaining something for the animal 

 economy. This becomes immediately comprehensible on the 

 assuuiption that hydrates of carbon subserve the most important 

 functions of muscular work. These substances do not lose any 

 of their importance as heat-producers in the ordinary sense of 

 the phrase, because in muscular work a great part of the heat 

 produced by oxidation is liberated as such, and because even 

 the heat converted into work is always at last changed back into 

 heat in the body of the animal ; for it is only exceptionally that 

 the animal is methodically employed by man for the production 

 of external mechanical work. 



There is another consideration connected with the preceding 

 one, which is well calculated to make our conclusion appear a 

 priori extremely probable. Among those animals whose muscles 

 have enormous strength, there are several whose nourishment 

 contains very little albumen, but, on the other hand, large quan- 

 tities of the hydrates of carbon, — for instance, the swift rumi- 

 nants, the goat, the chamois and gazelle, and many flying in- 

 sects. Is it conceivable that the great muscular exertions of 

 these creatures are really sustained by the oxidation of albumen ? 



