-_ oo,” 
Philosophical Conceptions of Life. 245 
Du Bois-Reymond. These observations have long been 
widely accepted as conclusive proof that natural currents exist 
in the quiescent nerve of the same general character as those 
attributed to the quiescent muscle, which I outlined a few 
minutes ago. ‘The electromotive force of this current was 
found by Du Bois-Reymond * to be equal to ‘022 Daniell in 
the sciatic nerve of the frog. When a nervous impulse passes 
along the nerve, the natural current is diminished; it expe- 
riences a negative variation, which, according to Bernstein ft, 
when the impulse results from a very potent stimulation, 
may more than neutralize the natural current. The same 
physiologist has shown that this negative variation moves 
along the nerves of the frog at the rate of 28 metres per 
second, that is, at the same rate as the nervous impulse itself, 
as determined without reference to the electrical phenomena. 
As in the case of the muscle-currents, these phenomena 
have been differently interpreted by Hermann {, who denies 
the existence of any natural nerve-current in uninjured nerves, 
and ascribes those observed in the experiments to the circum- 
stance that the parts of the nerve dead or dying, in conse- 
quence of the section, become negative to the living nerve. 
The negative variation produced by the stimulation of a 
nerve he explains by assuming that the stimulated part of the 
nerve becomes, in consequence of the changes resulting from 
the stimulation, negative to the unstimulated parts. I will 
not attempt to enter to-night into the merits of the contro- 
versy still in progress with regard to this question, nor will 
I pause to discuss the exceedingly curious and interesting 
phenomena of electrotonus §, concerning which I will only say 
that the question has even been raised by Radcliffe as to how 
far these phenomena are peculiar to nerves, and how far they 
may be regarded as mere phenomena of the electrical currents 
employed, which would be equally manifested under similar 
circumstances if a wet string or other bad conductor should 
be substituted for the nerve ||. 
However these disputes may be ultimately decided, what- 
ever the actual facts with regard to the electrical manifesta- 
tions In nerves at rest or in action may ultimately prove to 
* Du Bois-Reymond, Ges. Abh. Bd. ii. S. 250. 
+ Bernstein, op. cit. supra. 
¢ Hermann, loc. cit. supra, note *, p. 242; also Handb. der Phys. Bd. ii. 
Th. 1 (Leipsic, 1879), 8. 144 e¢ seq. 
§ See especially Du Bois-Reymond, ‘ Unters. Bd. ii. Th. 1, 8. 289, and 
Pfliiger, ‘ Unters. tber die Physiologie des Electrotonus’ (Berlin, 1859). 
An excellent summary of the observations (with the literature) is given 
by Hermann, ‘ Handb. der Physiologie, Bd. ii. Th. 1, 8. 157 e¢ seg. 
|| Radcliffe, p. 74 et seqg., op. cit. supra, 
