14 LOCALIZED ELECTRIZATION. 



tions {iihosphenes) at eacli intermission. These sensations are felt, 

 the first and most powerful, at the completion of the circuit ; the 

 second, much less powerful, at its interruption ; and the third, so 

 feeble as only to be perceptible in the dark, in the interval between 

 the two former. To whatever point of the face, or hairy scalp, the 

 moist galvanic rheophores are ajjplied, they always produce a suc- 

 cession of luminous sensations of a very dazzling kind, even with 

 an extremely weak current — provided that the region excited is 

 supplied by the fifth pair. The luminous sensation only affects 

 the retina on the same side as the galvanic excitation ; and it be- 

 comes larger and more brilliant as the exciters are brought nearer 

 I to the median line. Lastly, the light is perceived on each side, 

 J when tlie galvanic excitei'S are placed on the median line, where 

 the ramifications of the fifth pair of each side appear to be blended 

 together. We may even produce the electric phosphene by 

 galvanizing the chorda tympani ; but I have not been able to 

 do this with induced electricity. (I shall return to this subject 

 at a convenient opportunity.) The knowledge of this special 

 property of galvanism, which is only found in a degree infinitely 

 less developed in other kinds of electricity, is of the highest 

 importance in medicine, as the sequel will shew. 



It is, however, on the contractility of muscle that the inter- 

 mittent galvanic current displays a physiological power infinitely 

 greater than the continuous current. 



The galvanization of muscle by intermissions excites more acute 

 sensations than the electrization by induced currents. 



What is the action of continuous currents upon the vascular 

 nerves? I shall return to this important question in the third 

 chapter, which is devoted to a critical examination of the different 

 methods of electrization, and in which, after having tested com- 

 paratively the therapeutical action of continuous currents in the 

 treatment of atrophic paralysis and of atrophy, I shall have to 

 inquire whether the beneficial results obtained by the different 

 kinds of electricity can be explained on physiological grounds ; 

 or, in other words, whether we have any accurate knowledge of 

 their action upon the circulation and upon the vascular or trophic 

 nerves. 



rJ" § II. — Therajjeutical Properties. 



The galvanic excitation, which, when confined to the skin, may 

 produce there, besides very acute sensation, a considerable organic 

 effect, such as erythema, or vesication, or even an eschar, fulfils 

 certain special indications. It is adapted, for example, to the 

 cases in which it is desired to obtain at once an acute immediate 



