962 MESSRS, A. WALLER AND A. DE WATTEVILLE ON THE INFLUENCE 
nervous matter, '* a view in which he was followed by Cyon (‘ Principes d’Electro- 
therapie, Paris, 1872, p. 123), whose results were equally inconstant. Bruckner 
(Deutsches Klinik, 1868, No. 43) and Bunge (Arch. f. Klin. Med., 1870, p. 536) 
had recourse to the method of uniting the testing induction with the polarising 
galvanic currents in one circuit. They both obtained, in the main, similar results,— 
when the two currents flowed together, there was an increased effect both at the 
anode and at the kathode; when the two currents were opposed, the effect was 
diminished at both poles of the galvanic current, especially at the anode. In their 
interpretation, however, these two observers took opposite views. Bunge explained 
everything by an assumed “summation” of electromotive forces; Bruckner attributed 
the effects to physiological causes, though his arguments were not such as to carry con¬ 
viction. None of these experimenters, with the exception of Cyon, used the graphic 
method; they estimated the changes by watching the contractions. 
Methods and Bationale. 
We employed three modes of excitation: (1.) Induction currents; (2.) Makes and 
breaks of a continuous current; (3.) Mechanical stimulation. The electrodes* were 
applied as follows :—One electrode of large area—the “ indifferent” electrode—was 
applied to any convenient part of the body remote from the part explored; the other 
electrode of small area—the “ exploring” or “testing” electrode—was applied to 
selected points along the course of favourably situated nerves, and the effects at this 
movable electrode were alone considered. 
We shall describe these effects under the polar terms “anodic” and “ hathodic” 
without reference to any assumed direction of current in the nerve; for not only is 
the localisation of an efficient current in a given direction problematical for the 
imbedded nerve, but a simple experiment suffices to show that the position of the 
indifferent, whether central or periphera] to the exploring electrode, does not in any 
way influence the results obtained at either pole. 
The condition which we thought necessary to fulfil throughout our experiments was 
the coextension of the points of excitation and of polarisation; our reason being that 
owing to current diffusion and consequent establishment of opposite electrodes in the 
nerve in the immediate neighbourhood of the electrode, the electrotonic state is vari¬ 
able in kind, degree, and distribution. This condition is fulfilled by conjoining the 
testing and polarising currents in one circuit, and by applying one electrode only to 
the nerve.t The other method, by which the two circuits are separate, gave in our 
hands discordant results, similar to those of previous observers, who found that the 
* "We did not use nnpolarisable electrodes in these experiments, but plates of metal covered with 
chamois leather. 
t This method was first used by Eckhardt (Beitrage znr Anat. nnd Phys., Giessen, 1858-4, p. 28), 
afterwards by Pfluger (‘Elektrotonus,’ p. 394) and by von Bezold (‘Erregung der Nerven nnd Muskeln/ 
p. 212); on Man it has been employed by Bruckner (Zoc. cit .) and by Runge (loc. cit.). 
