ON LIVING MALAPTERURUS. 409 



the problem, of the immunity of electrical fish from the electric 

 current. On the contrary, it affords us an additional motive in our 

 efforts to solve it, in as far as it opens the prospect, that disclosures 

 of importance in relation to the general physics of muscle and 

 nerve will result from it. 



Pfliiger, who was a witness of my experiments (see above, p. 387), 

 and who at that time was working- at electrotonus, conjectured 

 that the Malapterurus may have power to put its nerves into a 

 state of anelectrotonus. But except under the influence of ex- 

 traneous currents, no trace of electrotonic conditions has ever been 

 observed in the nervous system. Pfliiger's theory seems to be con- 

 tradicted also by the following experiment. The electrical nerve of 

 the dying Malapterurus in the glass trough (see above, p. 406) had 

 been ligatured, and therefore could no longer be anelectrotonised by 

 means of its giant ganglion cells. Notwithstanding, it was not 

 excited by very strong alternating currents. 



There might be supposed to be some connexion between the 

 immunity of electrical fishes from the current, and the much dis- 

 cussed inexcitability of the spinal cord. This would be quite 

 arbitrary, for the same electrical nerve, which in the previous 

 experiment showed itself electrically unexcitable, gave a violent 

 shock at the moment of ligaturing the nerve, and in another 

 experiment, section acted in the same way. The spinal cord, on the 

 contrary, responds as little to mechanical as to electrical irritations. 



Since Briicke showed that muscles with the nerve removed, are 

 little sensitive to currents of short duration 1 , the fact that the 

 Malapterurus is also proof against the constant current of a battery 

 assumed much greater importance (see p. 407). Its immunity is 

 therefore not, like that of the muscles, connected with the duration 

 of the current. 



No other opinion seems to me to be left open, than that the 

 threshold of excitation lies higher for the nerves of the electrical fish 

 than for the nerves of other animals. I should have continued the 

 .investigation further in this direction myself, if opportunity had 

 been afforded to me. I rejoice all the more that Boll has recently 

 followed this track in the case of the Torpedo, apparently with good 



1 Sitzungsberichte der Wiener Akademie, u. s. w., 1867, vol. Ivi. Part ii. p. 594 ; 

 1868, vol. Ivii. Part ii. p. 125; Vorlesungen iiber Physiologic, 2 Ed. 1875, vol. i. 



p. 485- 



2 Archiv ftir Anatomic, u. s. w., 1873, p. 76. According to Steiner, the threshold 

 of electrical excitation in the Torpedo would lie below the thickness which a shock of 



