ON INDUCED CONTRACTIONS. 305 



part, and leaving a very small internal surface of the muscle exposed, that the differ- 

 ential current is found to be either null, or in the direction of the proper current. 

 This fact attracted my attention in the course of my early experiments, but the ex- 

 planation of it is clearer to me since my later investigations, reflecting that in leaving 

 the thigh almost entire, we have two elements, that is to say, the muscles of the leg, 

 and those of the thigh, which direct the current in the same direction, while there 

 is but one element of the muscular current which gives a current in a contrary di- 

 rection. 



Returning to the subject of this memoir, I would observe that I have employed a 

 muscular pile in the view of determining whether there is evolution of electricity in 

 the contraction of a muscle. But since in order to excite the contractions of the 

 muscle, I was obliged to bathe it with concentrated saline or acid solutions, or better 

 with alkaline solutions, I previously studied the effects of the action of these liquids 

 upon the muscular current. In this view, from a great number of frogs I selected 

 eight which I prepared in the usual manner, and which furnished sixteen elements 

 or half thighs. Closing the circuit, the needle reached 90° and remained stationary 

 at 22°. Constructing another similar pile, after having well-washed and then dried 

 the sixteen half thighs, the result was the same. Another sixteen similar elements 

 were immersed for a few seconds in a diluted solution of sulphuric acid, and after- 

 wards washed several times in water, so that they did not redden turnsol paper. 

 Composing the pile and closing the circuit, a current was produced in the direction 

 of the muscular current, but the deflection was only 6° or 7° at first, and the needle 

 was fixed at 0°. I rapidly cut the half thighs with a pair of scissors so as to renew 

 the internal surface of the muscle in a fresh state. Recomposing the pile, the current 

 was still weaker than that indicated above. Thinking that the effect of the acid 

 solution upon the muscular elements was to diminish the conductibility, I constructed 

 a muscular pile of eight half thighs of frogs taken from frogs previously intact, to 

 which I added four entire thighs taken from frogs likewise intact : the current which 

 resulted was 46°. In the room of the four entire thighs, I next substituted four entire 

 thighs which had been immersed in sulphuric acid and then washed, the current was 

 44°. The conducting power therefore had not varied in the muscular masses sub- 

 jected to the action of the acid solution. To be still more certain of this conclusion, 

 I tried the experiment already described, substituting eight half thighs for the four 

 entire ones for the purpose of prolonging the circuit. These eight half thighs being 

 treated with the acid solution, and joined together by contact of the internal surface 

 of one with the external surface of the other, the result was the same. 



I next repeated the same experiments, using a sufficiently concentrated solution of 

 potassa in which to immerse, for a few seconds, the muscular elements or half thighs. 

 These elements were then washed in pure water until they showed no alkaline re- 

 action. Composing the pile with sixteen elements, and closing the circuit, there 

 was a first deflection of from 10° to 12° in the usual direction of the muscular current. 



