40 LOCALIZED ELEOTEIZATION. 



The following experiments may' serve to show that the sensation 

 produced during faradization of the skin by dry rheophores, applied 

 to an equally dry surface, is entirely the result of cutaneous exci- 

 tation ; and that the sensation produced by the apj^lication of very 

 moist rheophores to the surface, on the level of a muscular plane, 

 can only be attributed to direct excitation of the muscle. 



First experiment. — Having found, in a wounded patient in the Hotel Dieii, 

 a part of the external crural mtiscle laid bare, I applied over the miiscle, and 

 on the denuded portion, a dry metallic rheophore. The resixlting contraction 

 was accompanied by a dull sensation, special to electro-muscular contraction. 

 I then placed the same rheophore on the plane of the same muscle, but upon 

 uninjured skin, and I obtained only a burning sensation, without muscular 

 contraction. Having replaced the metallic rheophore by moist sponges 

 contained in the exciting cylinders, and these being placed upon the skin, in 

 a plane corresponding to the crural muscle, I obtained contraction, with the 

 same peculiar dull sensation tliat was produced when the dry metalUc rheo- 

 phore was in contact with the denuded muscle. 



Second experiment.— A. patient, in wliom the radial nerve had been destroyed 

 by a bullet-wound of the lower part of the arm, had lost the sensibility and 

 the electric contractility of the muscles of the posterior region of tlie forearm ; 

 while the sensibility of the skin remained intact, from the integrity of the 

 cutaneous nerves. I applied the dry metallic rheophores on the skin of 

 the anterior and posterior antibrachial regions, and they produced an acute 

 burning sensation. I replaced the dry rheophores by the cylinders with 

 wet sponges, which produced in the posterior region neither sensation nor 

 contraction, although contractions attended by sensation were manifested in 

 the anterior region ; where also the biirning sensation produced by the di-y 

 rheophores was replaced by the dull and peculiar sensation of muscular 

 contraction. 



I have many times repeated similar experiments in other patho- 

 logical conditions, not only on muscles, but on mixed nerve- 

 trunks; and I have arrived at the conviction that the electric 

 excitation may reach a muscle or a nerve, without exerting any 

 action upon the skin in its course. 



It should, however, be remembered, that in certain cases sensa- 

 tions really produced by the excitation of the skin, or of the 

 cutaneous nerves, may be attributed to muscular sensibility alone. 

 In order to explain how such an error may be avoided, it is neces- 

 sary to enter into certain details. 



(a). It has just been shown by experiment that, if the skin 

 and the rheophores are sufficiently moist, and in perfect contact, 

 the former is traversed by the current without being excited ; and 

 that the electric recoraposition takes place more or less deeply in 

 the subcutaneous tissues. But at the moment when the rheo- 

 phores and the skin are brought into contact, and when contact as 

 yet is not perfect, the surface presents certain asperities which 

 occasion electric recompositions, attended by sensations of prick- 

 ing and burning, and even by crepitation and sparks, especially if 

 the current be that of the second helix, with its power of exciting 



