ON INDUCED CONTRACTIONS. 307 



as well as I was able : there remained a couple of thighs united by a portion of the 

 spinal chord. One of these thighs I cut in half, and in this manner I had a certain 

 number of elements all alike and consisting of an entire thigh, a portion of the spinal 

 chord, and a half thigh. It is easy to understand how, with these elements, I com- 

 posed a muscular pile, that is to say, applying the external surface of the entire thigh 

 upon the internal surface of the thigh of the succeeding element (fig. 13.). This done, 

 I immerse the extremities of the galvanometer in the liquid in which the extremities 

 of this pile terminate. A small appendage to the extremities of the conducting wires 

 of the galvanometer, precludes the necessity of my holding the latter with my hands 

 when I require to complete the circle. I have repeated this experiment a great 

 number of times, at one time using a pile of twelve, at another of sixteen, at other 

 times of twenty elements. Both the first deflection, and that at which the needle re- 

 mained stationary, were somewhat weaker than they would have been had tfie piles 

 been composed of an equal number of halves of thighs only. This difference is mainly 

 attributable to the greater length or resistance of the circuit. In every case referred 

 to above, after having suff'ered the needle to become stationary, which it did in the 

 various experiments at 10°, 12°, and sometimes 15°, 1 touched the lumbar plexuses of 

 the different elements with a sufficiently concentrated solution of potassa, excepting, 

 however, the two extreme elements, for fear the alkaline solution should reach the 

 liquid in which the extremities of the conducting wire of the galvanometer were im- 

 mersed. The muscular contractions took place immediately upon the application of 

 the alkali, and lasted for some seconds without ever being sufficiently strong to in- 

 terrupt the pile by displacing the elements. During these contractions the needle of 

 the galvanometer did not move. In some cases I have seen the needle go back, in 

 others rise to 2° or 3°. But these variations are too uncertain in the greater number 

 of cases, and most generally correspond to a too sudden motion of the elements of 

 the pile which disturbs their contact. 



Let us then conclude that direct experiment answers negatively to the question 

 we proposed to solve, whether there were evolution of electricity in muscular con- 

 traction. 



Having got rid of this part of the question, the next which presents itself is the 

 consideration of the phenomena which we observe in the proper current (for which 

 we employ whole frogs), and which consist in signs of increased intensity on first 

 touching the lumbar plexuses of the frogs with potassa, while, on the contrary, an 

 acid solution causes the needle to fall instantaneously. To arrive at a knowledge of 

 these facts I have repeated and varied my former experiments, and the explanation 

 of the facts is as follows : — 



Whatever be the form of the elements used for constructing the muscular pile, 

 that is to say, whether it be made of entire frogs, of halves of thighs, or, as described 

 (fig. 13.), if the surface of the muscular elements be bathed with an acid or alkaline 

 solution, it constantly happens, whether there be contractions or not, that the de- 



MDCCCXLV. 2 s 



