416 EE. Frankland on the Source of Muscular Power. 
expeditions, to take with them, as provisions, nothing but bacon- 
fat and sugar, because, as they say, these su stances are more 
nourishing than meat. They doubtless find that in fat and sugar 
they can most conveniently earry with them a store of force-pro- 
ducing matter. The above tables affirm the same thing. The 
5 lbs. potatoes, 1 ‘3 lb. of flour or pea-meal or of 341bs. of lean 
mentions the observations of Dr. M. C. We sind on the food : 
insects. The latter remarks, ‘‘ Many insects use during a period 
in which very little muscular work is performed food containing 
chiefly albuminous matter; on the contrary, at a time when the 
muscular work is very considerable, they live exclusively, or 
most exclusively, on food free from nitrogen.’ e also men-. 
tions bees and butterflies as instances of insects performing enor- 
mous muscular work, and subsisting upon a diet containing but 
the merest traces of nitrogen 
We thus arrive at the following conclusions: 
1. The muscle is a oe for the conversion nit potential en- 
ergy into mechanical for 
The mechanical oie of the muscles is derived chiefly, if 
not entirely, from the oxydation of matters contained in the 
ood, and not from the oxydation of the muscles themselves. 
In man the chief materials used for the production of mus- 
cular power are non- nitrogenous; but nitrogenous matters can 
also be employed for the same purpose, and hence the greatly 
increased evolution of nitrogen under the influence of a flesh 
diet, even with no greater muscular exertion 
4, Like every other part of the body, the muscles are con- 
stantly being renewed ; but this renewal is not perceptibly more 
ee during great muscular activity than during comparative 
uiescence. 
5. After the supply of es albuminized matters in the 
man to provide for the ssary renewal of the tissues, 
the best materials for the prolate. both of internal and exter- 
nal work, are non-nitrogenous matters, such as oil, fat, sugar, 
starch, gum, &c. 
a ®. The non-nitrogenous matters of food, which find thew way 
ee the blood, yield up all their potential energy as actual en- 
ergy; the nitrogenous matters, on the other hand, leave the body 
a wih a portion (one-seventh) of their potential energy unex- 
pen 
OL The transformation of potential energy into muscular power 
is pcan ok = by the production of heat within the 
body, uscular power is exerted externally. 
Thi is donbtleatt the chief and, probably, the only source of ani- 
heat. 
