ON INDUCED CONTRACTION. 
649 
in the act of contraction, and which consists in a different state of electricity in the 
different points of the contracted limb. 
3. This electrical phenomenon, like the contraction which produces it, lasts only 
for an instant. 
4. These electric states, developed by contraction, tend to produce electrical cur- 
rents which circulate in opposite directions across a conducting arch interposed be- 
tween the two limbs, which contract at the same time. 
5. The tenth experiment proves the existence of these currents and their direc- 
tions ; here we should remember that the galvanoscopic frog is more sensitive to the 
passage of the current when that current traverses the nerve in the direction of its 
ramification. Thus the contraction of the galvanoscopic frog, d (fig. 3), during the 
contraction of the limb, a, proves the existence of the electrical current, which goes 
from a towards d. The contraction of the galvanoscopic frog, c, during the contrac- 
tion of the limb, h, proves, in the same manner, the existence of an electrical current 
going from h towards c. 
Whatever the theory of these phenomena may be, it is certain that they demon- 
strate the production of an electrical disequilibrium in the act of muscular contraction. 
In the experiments which have been described, this electro-physiological phenomenon 
may consist in a species of discharge, propagated in muscles in the direction of the 
ramification of the nerves. Is the cause of this discharge a phenomenon analogous 
to that of electrical fish, or does it consist in a change in the natural conditions of 
the muscular current, produced by contraction ? In the present state of science it is 
impossible for us to answer this question. According to all the analogies, and 
according to our present experimental knowledge, we lean to the former of these two 
explanations; but we wait the light of new experiments to proceed safely further in 
this difficult field of science. 
Pisa, April 1, 1850. 
4 o 
MDCCCL. 
