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XXII. On the Influence of the Galvanic Current on the Excitability of the Motor 
Nerves of Man .* 
By Augustus Waller, M.D ., and A. de Watteville, M.A., B.Sc. 
Communicated by Dr. Burdon-Sanderson, F.R.S. 
Received February 2,—Read February 16, 1882. 
[Plates 64, 65.] 
Introduction. 
The verification for undissected nerve of the established laws of electrotonus for 
dissected nerve has been the object of several previous researches. Of some the 
results have been negative, of others contradictory, of but few fairly confirmatory. 
Peluger’s chief conclusions have received an occasional illustration from experiments 
made on Man, but these can hardly be said to carry support, still less independent 
proof. 
The first definite experiments on the subject were made by Fick (Medic. Physik., 
1866, p. 377). He tested his own ulnar nerve but failed to obtain any evidence of 
electrotonic change of excitability. Eulenburg (Arch. f. Klin. Med., 1867, p. 117) 
and Erb (ibid., pp. 238, 513) simultaneously came to opposite conclusions. According 
to Eulenburg, evidence of descending anelectrotonus and katelectrotonus was uni¬ 
formly obtained by testing the nerve below the ascending and descending galvanic 
currents respectively. Erb, on the contrary, found the excitability diminished below 
the kathode, increased below the anode—an apparently anomalous result which 
Helmholtz (Nat. Med. Verein., Heidelberg, 1867) attributed to rapid current- 
diffusion, and consequent establishment in the vicinity of the electrode, of opposite 
“ odic” points in the nerve, wherever the current enters or leaves it. And, in effect, 
acting on this suggestion by testing the nerve with a small electrode, introduced 
through a large perforated electrode (polarising), Erb found the excitability diminished 
during anodic, increased during kathodic influence. Samt (‘Her Electrotonus am 
Menschen/ Berlin, 1868), who also sought for descending electrotonus, came to similar 
conclusions as Eulenburg, though his experiments were far from yielding uniform 
results; he attributes the inconstancy of the results to the “ inconstancy of the 
* Towards tbe expenses of tbis research, a grant was made by the British Medical Association on the 
recommendation of the Scientific Grants Committee of the Association. 
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