ISO MUSCULAR CURRENT. LECT. IX. 



The contractions which you have seen excited in the gal- 

 vanoscopic frog, already give you an idea of an electric 

 current, which I shall call muscular ; which, derived from 

 the muscle of a living or recently killed animal, in which it 

 is produced, circulates in the nerve of the frog. 



But it is necessary to have recourse to the galvanometer 

 to place beyond doubt the existence of this current, to dis- 

 cover its direction, and to determine its intensity relatively 

 both to the condition of life or death, and to the position of 

 the animal in the scale of beings ; in a word, to study its 

 laws. 



I expose the pectoral muscle of a living pigeon, I make 

 a wound in it, and quickly convey the two platinum ex- 

 tremities of a very delicate galvanometer, the one to the 

 external surface of the muscle, the other to the interior of 

 the wound. You perceive that the needle instantly de- 

 viates from 15, to 20, and even more ; thus demonstrating 

 the existence of a current, whose direction is from the in- 

 ternal part of the muscle to the surface of the same muscle. 

 The needle soon comes back, and oftentimes returns to 0. 

 If I remove the extremities of the galvanometer from within 

 the wound, and then a moment afterwards recommence 

 the experiment, it sometimes, or rather, most frequently 

 happens, that I obtain a new deviation in the direction of 

 the first, but always more feeble. In some cases, however, 

 the succeeding deviations are in the reverse direction of 

 the first ones. By repeating the experiment on the muscles 

 of other animals, the first indication furnished by the gal- 

 vanometer is obtained, in most instances, like that which 

 we have witnessed ; but it is right to say that afterwards, in 

 the succeeding experiments, the currents are often inverse 

 to the first. Such a fact, then, is not very clear: it does not 

 rigorously prove the existence of the muscular current. If 

 I had experimented in, like manner on a dead animal, you 



