APPENDIX II. 139 



of a given weight of muscle in the human body. 

 Fick and Wislicenus refer to this missing link in 

 the following words : " The question now arises 

 what quantity of heat is generated when muscle is 

 burnt to the products in which its constituent 

 elements leave the human body through the lungs 

 and kidneys ? At present, unfortunately, there are 

 not the experimental data required to give an 

 accurate answer to this important question, for 

 neither the heat of combustion 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 combustion than they otherwise would have 

 been, whilst similar determinations, which have been 

 made by Edward Smith, Haughton, 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 calorimetrical determination of the actual 

 energy evolved by the combustion 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 into the actual organized 

 substance of the muscle, before its oxidation can 

 give rise to mechanical force, or whether it is not 



