September 10, 1870.] THE PHARMACEUTICAL JOURNAL AND TRANSACTION . 
203 
is, in the state of rest, distributed in the apparatus 
for the production of the force, or is applicable for 
other purposes in the animal; the force is not gene¬ 
rated at the moment of its application. 
It is evidently dependent upon the will of the 
animal, determined by the nerves, to bring about 
such an arrangement in the parts of its electrical 
apparatus that the distributed free electricity may 
be collected and applied in giving shocks. Frequent 
discharges fatigue the animal, and rest as well as 
food are requisite in order to renew the accumula¬ 
tion of electricity. 
The nerves in the muscular appara tus appear to 
act in a similar manner; under their influence the 
metamorphosis which is constantly going on receives 
a special direction in such a manner that the exist¬ 
ing molecular motion is converted into a motion of 
mass. 
Any more detailed explanation of the processes 
taking place in muscles by which contraction is de¬ 
termined, and upon which their capability of per¬ 
forming work depends, would have to be regarded as 
hazardous in the present state of our knowledge. 
The only points in regard to which we are no 
longer in doubt are that the muscular force is not 
produced like the motive power in a steam-engine, 
and that the simple assumption of its being pro¬ 
duced by combustion of non-nitrogenous or nitro¬ 
genous substances in muscle leaves us without any 
help in regard to this obscure subject; it is a mere 
formula without meaning which perplexes more 
than it asserts. 
When a constituent of a muscle produces a me¬ 
chanical effect, it must undergo chemical alteration 
from its soluble and mobile constituents; there 
must be other compounds formed gradually, and this 
must continue so long as the muscle is capable of 
performing work. Subsequent more exact investi¬ 
gation will render this more intelligible; and for the 
present it may be said with certainty that among 
the products thus formed urea is not one, for it is 
not to be detected either in the living muscle or in 
muscle that has been separated from the body. 
Hence it necessarily follows that muscular work 
and the production of urea do not bear any direct 
relation to each other, consequently the work per¬ 
formed during a certain time cannot be measured 
by the quantity of urea secreted during that time. 
The astonishing observations of Dr. Parkes* do 
not, as I believe, admit of any doubt in regard to 
this point. I regard them as the basis of the true 
law by which we have to judge as to the metamor¬ 
phosis of muscle in the animal body. 
These experiments were made upon two healthy 
soldiers (S. and B.) of dissimilar bodily weight. 
Dining sixteen days they consumed in their food 
equal quantities of nitrogen. Their food consisted 
of bread, meat, vegetables, etc., in such proportions 
that their bodily weight was maintained almost con¬ 
stant. The experiments were divided into five 
periods. During the first period both men did their 
usual work; during the second they remained for 
the most part at rest and in bed ; during the third 
period they did their ordinary work; during the 
fourth period they were put to severe exertion, on 
the first day making a march of twenty-four En¬ 
glish miles over level ground, and on the second day 
.a march of thirty-five miles; during the fifth period 
* ‘Proceedings of the Royal Society,’ No. 94. 18G7. 
they did their usual work. The quantities of urea 
secreted dining these five periods were as follows :— 
I. Ordinary Work. 
Grams. 
Mean of 4 days. S. ... 36"374 
„ B. . . . 37T34 
II. Rest. 
Mean of 2 days. S. . . . 38-348 
„ B. . . . 39T00 
III. Ordinary Work. 
Mean of 4 days. S. ... 36*223 
„ B. . . . 37*534 
IV. Severe Exertion . 
Mean of 2 days. S. . . . 38'643 
„ B. . . . 40-328 
Y. Ordinary Work. 
Mean of 4 days. S. ... 40-811 
„ " B. . . . 38-909 
These results seem to me to demonstrate unmis¬ 
takably that the nitrogenous compounds eliminated 
during muscular exertion are ultimately excreted as 
urea, and that this does not take place completely at 
the time the work is done, but at a later period. 
During the second period the quantity of urea 
excreted by both individuals while at rest was in¬ 
creased ; during the third period it was the same as 
in the first period; it increased considerably during 
both of the days of marching; while in the fifth 
period of ordinary work it was always higher than 
during the first and third periods. 
Conformably with these results the bodily weight 
decreased during the second period, while it increased 
during the third period, again decreased most con¬ 
siderably during the fourth period, and was restored 
to its original state during the fifth period. 
Dr. Parke’s memoir on the excretion of nitrogen 
during rest and work with non-nitrogenous diet also 
contains a large number of remarkable results, which 
cannot be discussed here with one exception. 
The loss of weight suffered by both individuals 
during a long march was very considerable, both 
with ordinary diet and with non-nitrogenous diet. 
In the case of S. the loss of weight during this 
period amounted to 5 pounds and 4 pounds; in the 
case of B. it was 4f and 1^ pound. The reason for 
this loss of weight cannot be doubtful. Both indi¬ 
viduals may have lost fat by a greater consumption 
of oxygen during the severe work; but the greater 
part of the loss was undoubtedly water; not, indeed, 
liquid water that could be replaced by drinking, but 
water that was combined in the muscles and tissues, 
and had been set free in consequence of the meta¬ 
morphosis or consumption of muscular substance; 
the slow restoration of the .bodily weight and the 
necessary co-operation of the food prove that the 
tissues, which in their natural condition had retained 
the water eliminated, were altered in their character; 
four days elapsed in the case of S. and B. before 
they had again acquired their original weight. 
The animal organism has frequently been com¬ 
pared to a railway locomotive in which, by the joint 
action of air, water and fuel, heat and power are 
produced. In reality air, water and food, which 
may in a certain sense be regarded as fuel, are ne¬ 
cessary conditions for the production of heat and 
