220 PISCES. 



the muscles of the caudal fin, and is also invested by an aponeurotic 

 covering : it resembles in form a three-sided prism. The internal 

 structure of the electric organ is essentially similar to that of the 

 Torpedo, with this difference only, that the columns lie horizontally 

 upon each other, instead of standing perpendicularly. They resem- 

 ble a row of horizontal bands, are much shorter than in the Electric 

 Rays, and their septa are placed perpendicularly, owing to the po- 

 sition of the columns. The number of the septa admits of being 

 only proximately reckoned j in an adult Electrical Eel there may be 

 perhaps several millions. The nerves that enter these organs in the 

 Eel are all spinal nerves ; neither the cerebral nerves nor the lateral 

 nerves giving branches to them. The number of nervous trunks 

 amount always to above two hundred, and from these sensitive 

 branches pass* off also to the integument. It would appear, too, 

 that the anterior or inferior motor roots of the spinal nerves, whose 

 branches are distributed to the electric organs, are more strongly 

 developed. 



In the Electric Silurus, with the more minute anatomy of which 

 we are unacquainted, the electric organs extend immediately beneath 

 the integument from the fore part of the head and the branchiae to 

 the anal fin. An external and an internal organ may be distin- 

 guished, which receive their nerves partly from the n. vagus and 

 partly from the spinal nerves. 



We know now, from the numerous experiments that have been per- 

 formed, principally in Europe, by eminent philosophers upon living 

 specimens of Gymnoti. that the electricity generated in the apparatus 

 of these animals can be discharged by the voluntary exercise of 

 their nervous influence, and that what is called animal electricity 

 is perfectly analogous to that which is produced by the Leyden jar 

 or voltaic pile. Some experimenters have gone so far as to succeed 

 in obtaining from the Gymnotus an electric spark ; aberrations also 

 of the magnetic needle have been observed, and it is probable that 

 heat also is developed, during the discharge. The Electric Eel is 

 capable of producing the most violent shocks, sufficient indeed to 

 stun and throw down men and horses. 



