202 Mr H. F. Baxter on Muscular Power. 
After each experiment the plates were removed from the 
cell of the battery and rinsed in clean water. 
Judging from the results obtained in this experiment, I 
consider that the normal power of the gastrocnemius muscle 
of this frog was capable of raising 4 oz. (to which must be 
added 2 drs. for the weight of the scale) 1°, or #sd part of 
an inch. 
As the mode in which the weights are added have great 
influence over the results, it is necessary to be acquainted 
with it. If the weight be rather heavy in the first instance, 
the elongation of the muscle takes place gradually and con- 
tinuously, and unless the index be carried sufficiently back 
before the muscle is made to contract, the full amount of 
contraction will not be obtained; and if the weight be too 
heavy for the muscle, it acts by exhausting the muscular 
power or by overstretching the muscle. If the weight be 
not sufficiently heavy to elongate the muscle, the amount 
of contraction is not greater than with a heavier weight, 
proving the correctness of the conclusion arrived at by 
Schwann, that the contractile power of a muscle is greater 
the more it is elongated. There is a limit to the natural 
elongation of a muscle, and this limit it is somewhat diffi- 
cult to ascertain. It is not indicated by gradually adding 
the weights to the scale until contraction is just excited, 
but more by the permanency and constancy of the results 
when the experiment is repeated. The criterion which I 
think may be acted upon with safety is this—commence 
with a medium weight, and note the results obtained by 
increasing the weight ; if the muscle continues to elongate, 
and if the index has a tendency to recede, we are getting 
beyond the limit of its natural elongation. If by diminish- 
ing the weight the index has a tendency to advance or to 
retain its position, we have now obtained some indication 
of its natural power. In the experiment detailed I began 
with a medium weight,—4 oz.,—and the index was brought 
to 89; 6 oz. were afterwards added, this brought it to 35, 
and during the contraction it fell to 34; 4 oz. were then 
added, it arose from 35 to 36, and retained that number. 
If we cast our eye over the results, we find that the heavy 
weight evidently exhausted the power of the muscle, and 
