412 , Frankland on the Source of Muscular Power. 
ments regarding the amount of carbonic acid evolved from his 
own lungs under different circumstances,” : 
Excretion of carbonic acid during rest and muscular exer- 
tion :— 
Carbonic acid 
per hour. 
During sleep, - - - - . - 19°0 grams, 
Lying down and sleep approaching, = - - - 28:0: =." 
In a sitting posture, - - - - ‘. 29:0 2.5 
Walking at rate of 2 miles per hour, - - - 106-, 
ay i “ : “ a = a 100°6 “ec 
On the treadwheel, ascending at the rate of 28°65 feet 
per minute, - - - - 189-6 
It has been already stated as a proposition upon which all are 
agreed, that food, and food alone, is the ultimate source from 
which muscular power is derived; but the above determinations 
and considerations, the speaker believed, prove conclusively, first- 
ly, that the non-nitrogenous constituents of the food, such as 
starch, fat, &c., are the chief sources of the actual energy, which 
becomes partially transformed into muscular work ; and secondly, 
that the food does not require to become organized tissue before 
its metamorphosis can be rendered available for muscular power ; 
its digestion and assimilation into the circulating fluid—the blood 
—beirg all that is necessary for this purpose. It is, however, by 
no means the non-nitrogenous portions of food alone that are ca- 
pable of being so employed, the nitrogenous also, inasmuch as 
they are combustible, and consequently capable of furnishing ac- 
tual energy, might be expected to be available for the same pur- 
pose, and such an expectation is confirmed by the experiments 
of Savory upon rats,” in which it is proved that these animals 
can live for weeks in good health» upon food consisting almost 
exclusively of muscular fibre. Even supposing these rats to have 
. 
nitrogenous constituents of food is for the renewal of muscular 
y which is in part transmuted into muscular force. 
ca 
active energy, one portion assum- 
the brain to the muscle, the nervous agent determines oxydation. 
ihe potential energy becomes active 
ing the form of motion, another appearing as heat. Here is 
* Phil. Trans. for 1859, p.709. The Lancet, 1868, pages 381 and 412. 
courses through the muscle, but when the muscle is at rest there 
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a 
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4 
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