226 LOCALIZED ELECTEIZATION. 



neuralgia, afterwards by diminished sensitiveness to the electric excitation. The 

 paralysis of motion was complete, the sense of taste was lost on the ailected side of 

 the tongue, and the condition of the soft palate was normal. From the end of 

 October to the 4th of December the induced current was applied daily for half an 

 hour without result. Neumann then had recourse to the continuous current, which 

 by the 24th of January had produced considerable improvement. The induced 

 cm-rent at first produced no reaction, in whatever strength it was applied or wherever 

 the electrodes were jjlaced. With the beginning of the return of volitional control 

 over the muscles there appeared also a trace of reaction to faradism. This appeared 

 only on direct muscular excitation, and was much less on ihe diseased than on the 

 healthy siiie. The continuous current, on the contrary, produced stronger contractions 

 on the diseased side than on the healthy. By the application only of from six to 

 eight of Siemens' elements contraction was produced on the former, but not with less 

 than from ten to twelve elements on the latter. On the healthy side, witli from 

 fourteen to sixteen elements, reaction could be produced either by intra-muscular or 

 extra-muscular excitation, while on the diseased side it was only produced by the 

 direct method. 



In this case Neumann in.stitiited experiments calcnlated to afford a physical 

 explanation of the difference of action of the two cnrrents. He finds the 

 physical peculiarities of the induced cui-rents, as compared with continuous 

 currents, to be in the rapid succession of currents separated by intervals, in 

 their alternating direction, and in their momentary individual duration. A 

 fom"th possibility, tliat the strength of the single induced currents may be 

 somewhat less than the strength of the continuous battery current, and that 

 this may exphiin the inefficacy of the former, may at once be set aside by the 

 foregoing ; since a current from six of Siemens' elements, when the human 

 body is included within its circuit, produces a scarcely appreciable reaction, 

 and induced currents from superimposed coils produce an unbearably strong 

 reaction. 



In order to test the first three points of difference, the hammer of an 

 induction apparatus was secured ; and a cup of mercury, with wires dipiMng 

 into it, arranged so as to form part of the circuit of the induced current. By 

 raising and again dipping the wires, completion and interruption induction 

 shocks were obtained, and it was foimd that neither the stronger interruption 

 shock, nor the Aveaker completion shock, produced contractions on the para- 

 lysed side, although the completion shocks in the same experiment acted 

 powerfully upon the sound side. Hence it appeared that neither tlie rapid 

 succession of the individual induction shocks, nor their alternating direction, 

 could be the cause of their inefficacy, and hence only their brief duration 

 remains to be considered. The following experiment may serve for proof. 

 Neumann reduced the duration of the battery current to the smallest appre- 

 ciable time by introducing into the circuit a mechanism in which a fine 

 platiniim wire was drawn quickly over a little jDlate of wood in which a thin 

 plate of platinum was inserted, with its edge level with the surface. The 

 current only passed wliilst the wire and the plate of platiniim were in contact, 

 and the electrodes being iirst put in position, the circiiit was thus completed. 

 He found that the strongest battery current was thus rendered almost 

 ineffectual on the paralysed side, although on the sound side it produced 

 active contraction. If one electrode was placed on the paralysed cheek, the 

 other on the chin exactly in the median line, and then a current from fifty 

 elements was allowed to pass through the above described apparatus, the para- 

 lysed side showed only a trace of contraction, while the soiind side, although 

 lying outside of the jn-oper course of the current, was more strongly moved. 

 The principal current acted with less power on the jiaralysed side than the^ 

 side ciu'rent on the sound side, and Neumann has observed the same thing 

 with strong induction shocks in the same position of the electrodes. 



Neumann replies as follows to the question a^ to the nature of the physical 

 difference of the induced and of the battery currents in their action upon 

 paralysed nerves. The excitability of the paralysed nerves and muscles as 

 against momentary currents — even when of considerable strength — is lost; 

 but their excitability as against currents of greater than momentary dura- 



