646 
PROFESSOR MATTEUCCI’S ELECTRO-PHYSIOLOGICAL RESEARCHES. 
from the galvanometer signs of electrical phenomena produced by the act of contrac- 
tion. The variations produced in the conductibility of the circuit, by the convulsive 
movements of the muscles of the frogs, which alter the points of contact between the 
elements of the pile, the agitation of the liquid into which the platina plates of the 
galvanometer are plunged, are constant and inevitable causes of the production of an 
electric current, which involves a constant uncertainty as to the effects which may 
depend on contraction. These same causes of error exist in the experiment made by 
M. DU Bois Reymond on voluntary contraction of a man’s arm ; 1 have tried a great 
number of experiments, following his method, increasing the number of elements 
which contract at the same time, without ever succeeding in obtaining an evident and 
constant development of electricity by muscular contraction. In the researches for 
the discovery of this development, I have not failed to employ, with all proper care, 
the galvanoscopic frog. Operating on a circle of thirty and forty individuals, who 
all contracted the same arm at the same time, and although the galvanoscopic frog, 
the nerve of which formed part of the circuit (being in contact with the two outer- 
most fingers of this pile of men), was extremely sensitive, yet never did we obtain the 
slightest sign of a current from voluntary contraction. Yet the circuit, though com- 
posed of a great number of individuals, was always a sufficiently good conductor for 
the transmission of a current of some muscular elements, capable of producing con- 
traction in the galvanoscopic frog. 
Since, therefore, the galvanometer employed in my first experiments on induced 
contraction, and by means of which M. du Bois Reymond thinks that he has disco- 
vered the development of electricity in voluntary muscular contraction, never has 
with me led to any other but uncertain and very doubtful results, since by the aid 
of the galvanoscopic frog, used as a substitute for the galvanometer, I have never ob- 
tained the slightest signs of an electric current in the voluntary contraction of the 
muscles of the arms, I was authorized in concluding that the development of elec- 
tricity by muscular contraction still remained to be demonstrated by experiment, 
and that the phenomenon of induced contraction was still that which led most 
directly to this result. 
I will now give some new experiments on induced contraction, of incontestable evi- 
dence and certainty, and which undoubtedly lend an increasing probability to the 
conclusion that induced contraction is due to an electric discharge, and that muscular 
contraction is accompanied by a development of electricity. 
Exp. 1. I prepare a frog in the usual manner, and I lay on the muscles of its 
thighs, legs, and on the articulations of its claws, the nerves of highly sensitive gal- 
vanoscopic frogs : on provoking the contraction of the muscles of the first frog by 
irritating its lumbar nerves, the galvanoscopic frogs contract, and when these first 
contractions are very violent, induced contraction may be seen to take place on 
contact even with the extremities of the limb of the entire=^ frog. The signs of in- 
* I apply the word entire to the frog fastened on the glass tubes : see figs. 1 and 3. 
