390 OBSERVATIONS AND EXPERIMENTS 



anterior side of the plates. The direction of the shock ought 

 therefore to be, as Max Schultze already supposed, the same as that 

 in Malapterurus 1 . According to Robin, it would be the opposite 2 . 

 He did not himself perceive the bearing of his statement ; this is 

 not to be wondered at, as he did not even know that the direction 

 of the shock is different in the Gymnotus and Malapterurus 3 . 



7. Physical Investigation of the shock of the Malapterurus. 



The discovery of the Ley den jar, towards the middle of last century, 

 quickly put an end to t|ie theories of the older physicists as to the 

 shock of electrical fish, and its explanation by stupefying emanations 

 or mechanical shock. After Adanson on the Senegal, in 1751, had 

 observed the similarity of the discharge of the Leyden jar and of 

 the sensation produced by the Malapterurus 4 , the endeavour arose to 

 prove the identity of the cause of both phenomena in other ways. 

 The attempt was made to reproduce by means of the shock 

 of electrical fish other electrical actions, and particularly to show 

 that the conductors and non-conductors of both are the same. In 

 spite of the efforts of Walsh 5 , Cavendish 6 , Configliachi 7 and others, 

 there still remained sufficient uncertainty in regard to this point 

 to induce Humphry Davy 8 to express shortly before his death, the 

 opinion that the electricity of electrical fishes might be different 

 from ordinary electricity. Faraday, indeed, only four years later, 



had wasted away to the tendinous sheath. Unfortunately, he could not ascertain if 

 this arose from individual differences, or if it was a question of periodical conditions 

 dependent on the season of the year and spawning time (Naturwissenschaftliche 

 Eeise nach Mossambique, etc., loc. cit. p. 33). For further testimony as to the 

 inactivity of the organs of Monnyrus, see Hartmann, in the Archiv fur 

 Anatomic, etc., 1861, p. 653. Herr Babuchin, however, records a shock of Mor- 

 myrus (Centralbl. etc., loc. cit. p. 163). Goodsir communicated to me his surmise 

 (if he has printed it, I know not) that the pseudoelectric organs of the common 

 skate are electrically active only during sexual excitement. 



1 Archiv fur Anatomic, etc., 1858, p. 213. 



3 Comptes rendus, etc., 1865, vol. Ixi. p. 239; Journal de I'Anatomfe et de la 

 Physiologic, etc. By M. Ch. Kobin 2 me Annde, 1865, pp. 507, 577. 



3 * Ainsi dans I'appareil electrique des rates, comrne sur le Gymnote et le Malap- 

 terure, le courant est comtamment dirigt, de VevtremiU cephalique vers Vextremite 

 caudale' (i.e. in the wire of the multiplier). 'La direction du courant montre qn.e 

 le p6le positifest toujours vers sa partie anterieure, et le pdle negatif vers sa partie 

 posttrieure.' Journal, etc., 1. c. p. 588). 



4 Histoire Naturelle du Se'ne'gal, Adanson. Paris, 1757, p. 135. 

 6 Philosophical Transactions, etc., 1773, p. 461. 



6 Ibidem, 1776, p. 196. 



7 L'identita del Fluido elettrico col cosl detto Fluido galvanico vittoriosamente 

 dimostrata, etc. Pavia, 1814, 4. p. 141, in. 



Philosophical Transactions, etc., 1829, p. 17. 



