INDUCED ELECTRICITY. 25 



second helix, when he lield both rheophores in the same hand. 

 The observation led me to institute a series of experiments, which, 

 repeated frequently, and on many persons, have always given the 

 same results. 



If, after having equalized tlie force of tlie currents of the first, 

 and of the second helix, by taking in each hand a moist rheophore, 

 and obtaining from each current an action tliat is felt, let us say, 

 as far as to the elbows, their action is compared anew by taking 

 both cylinders into one hand, freely moistened (it being well 

 understood that the cylinders do not touch eacli other), it will be 

 found that the sensation produced by the current of the first helix 

 is more acute, and more penetrating than that produced by the 

 current of the second. These j)henomena of sensibility are the 

 more pronounced, the more rapid the intermissions. The sensa- 

 tions and contractions, limited to the hand that liolds the two 

 moist rheophores, result from the direct action of the current upon 

 the subcutaneous nerves of the palmar surface of the hand and 

 fingers, and upon the muscles of that region. 



The current of the first helix produces also a more acute sensa- 

 tion when it is directed upon the muscles of other regions of the 

 body. 



There are some muscles in which it is easy, by reason of their 

 isolation, to display this special action of the current of the first 

 helix upon the muscular sensibility. I may mention, as examples, 

 the deltoid and the supinator longus, on the middle part of which 

 the exciting sponges may be placed as near together as possible. 

 If in such experiments we place the two currents in identical con- 

 ditions by equalizing their tension (by means of a tube of water), 

 we may see how the current of the first helix excites most the 

 muscular sensibility. But when we experiment in regions where 

 the muscular layers are more or less thick, and are superimposed 

 on one another, the difference of action of the two currents on the 

 muscular sensibility is less easy to display ; because the current 

 of the second helix is of a greater tension than that of the first, 

 and, as I will soon explain, its recomposition takes place more 

 deeply — so that a large number of muscular fibres are thrown into 

 contraction, and sensation is proportionately augmented. 



It would be reasonable to infer that the sensibility of other 

 organs more or less deeply seated beneath the skin would also be 

 more acutely excited by the current of the first helix than by that 

 of the second. I have proved this for many of them ; for the 

 mixed nerves, the testes, the bladder, the rectum ; and for these 

 the difference of sensation excited by the two currents is con- 

 siderable. 



