210 ELECTRIC FISHES. L.ECT. X. 



the proper current of the frog, because, until recently it 

 was in the frog alone that we could recognise its existence. 



I have endeavoured to ascertain what part of the inferior 

 extremity of this animal was necessary to the production 

 of the current, or what influence the different parts of the 

 limb had upon it. I will show you an experiment which 

 will solve these questions. 



Here are two piles opposed to each other, earh formed 

 of the same number of elements. One of them is com- 

 posed of six frogs, prepared according to the method of 

 Galvani, the other of six legs only, the thighs and spinal 

 nerves being removed. The six elements of the first touch 

 the six of the other ; but their arrangement is inverse, so 

 that at the point of the junction there come in contact, on 

 one side, nerves, and on the other, the upper end of the 

 leg. Thus the two piles are opposed : I put the wires 

 of a galvanometer in connexion with the two extremities 

 of the two piles, and I obtain no signs of a differential 

 current. 



The proper current of the frog has, then, for the organic 

 element, the leg only. 



Recently, by studying more attentively the proper cur- 

 rent, I have satisfied myself that it is a phenomenon which 

 appertains to all animals. Here is the enumeration of the 

 fact : in every muscle endowed with life, in which the ten- 

 dinous extremities are not equally disposed, there exists 

 a current directed from the tendon to the muscle, in the 

 interior of the latter. All animals have some muscles, in 

 which one tendinous extremity is narrower than the other ; 

 and which, at one part, forms a kind of cord, and at the 

 other, becomes broader and riband-like. In the frog, and 

 many other animals, the gastrocnemius has this character : 

 in birds, the pectoral muscle presents this arrangement. 

 When we form a pile with these muscles, we find that a 



