252 ON THE SOURCE OP MUSCULAR POWER. 



taut question, for neither the heat of comhustion of muscle nor of the. 

 nitrogenous residue (urea) of muscle is known." Owing to the want 

 of these data, the numerical results of the experiment of Fick and 

 "Wislicenus are rendered less conclusive against the hypothesis of 

 muscle comhustion than they otherwise would have been, whilst simi- 

 lar determinations, which have been made by Edward Smith, Ilaugh- 

 ton, Playfair, and others, are even liable to a total misinterpretation 

 from the same cause. 



The speaker stated that he had supplied this want by the calori- 

 metrical determination of the actual energy evolved by the combus- 

 tion of muscle and of urea in oxygen. Availing himself of these 

 data he then proceeded to the consideration of the problem to be 

 solved, the present condition of which might be thus summed up : — 

 It is agreed on all hands that muscular power is derived exclusively' 

 from the mutual chemical action of the food and atmospheric oxygen; 

 but opinions differ as to whether that food must first be converted in- 

 to the actual organized substance of the muscle, before its oxidation 

 can give rise to mechanical force, or whether it is not also possible 

 that muscular work may be derived from the o::ddation of the food, 

 which has only arrived at the condition of blood and not of organized 

 muscular tissue. 



The importance of this problem can scarcely be overrated ; it is a 

 corner-stone of the physiological edifice, and the key to the pheno- 

 mena of the nutrition of animals. For its satisfactory solution the 

 following data require to be determined : — 



1st. The amount of force or actual energy generated by the oxida- 

 tion of a given amount of muscle in the body. 



2nd. The amount of mechanical force exerted by the muscles of 

 the body during a given time. 



3rd. The quantity of . muscle oxidized in the body during the same 

 time. 



If the total amount of force involved in muscular action, as mea- 

 sured by the mechanical work performed, be greater than that which 

 could possibly be generated by the quantity of muscle oxidized during 

 the same time, it necessarily follows that the power of the muscles is 

 not derived exclusively from the oxidation of their own substance. 



As regards the first datum to be determined, it is necesssary to 

 agree upon some unit for the measurement of mechanical iorce. The 

 imit most commonly adopted is that represented by the lifting" of a 



