648 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



the muscles, he makes use of data furnished by several experi- 

 ments. Fh'st, by that of Fick and Wislicenus, who estimated the 

 amount of work done by them in ascending the Faulhorn mountain 

 in Switzerland. Second, by Dr. E. Smith, who calculated the 

 force exerted by prisoners engaged in a treadmill. Third, by Dr. 

 Haughton, who found the external work done by the military 

 prisoners employed in shot-drill and fed on vegetable diet. Fourth, 

 by Professor Playfair, who determined the average work per- 

 formed by pedestrians, pile-drivers, porters, &c. Lastly, Professor 

 Frankland gives his own experiments with various kinds of food 

 for determination of the amount of power produced by oxydation 

 and conversion of each. From all the facts adduced, he draws 

 the following conclusions : 



1. The muscle is a machine for the conversion of potential 

 energy into mechanical force. 



2. The mechanical force of the muscle is derived chieflj^ if not 

 entirely, from the oxydation of matters contained in the blood, 

 and not from the oxydation of the muscles themselves. 



3. In man the chief materials used for the production of muscu- 

 lar power are non-nitrogenous ; but nitrogenous matters can be 

 also employed for the same purpose, and hence the greatly-in- 

 creased evolution of nitrogen under the influence of a flesh diet, 

 even with no great muscular exertion. 



4. Like every other part of the body the muscles are constantly 

 being renewed, but this renewal is not perceptibly more rapid 

 during great muscular activity than during comparative qui- 

 escence. 



5. After a supply of sufiicient albuminized matters in the food 

 of man to provide for the necessary renewal of the tissues, the 

 best materials for the production, both of internal and external 

 work, are non-nitrogenous matters, such as oil, fat, sugar, starch, 

 gum, &c. 



6. The non-nitrogenous matters of food which find their way 

 into the blood, yield up all their potential energy ; the nitro- 

 genous matters qn the other hand, leave the body with a portion 

 (one-seventh) of the potential energy unexpended. 



7. The transformation of potential energy into muscular power 

 is necessarily accompanied by the production of heat within the 

 body, even when the muscular power is exerted externally. This 

 is doubtless the chief, and, probably, the only source of animal 

 heat. 



