146 



A HISTORY OF FISHES 



substance, and is further subdivided by thin partitions into a 

 number of small compartments, each containing a flat electric 

 plate. On one side of the plate is a cluster of fine nerve tendrils, 

 which unite and join the main nerve supplying the whole organ, 

 and this is in turn connected with a special lobe of the brain. 



Fig. 61. 



Electric Ray {Torpedo) dissected to show one of the electric organs with the 



associated nerve supply. The prismatic areas on the surface of the organ indicate 



the vertical columns of electric plates, of which there may be 500,000 in each 



organ. (After Gegenbaur.) e.o., electric organ. 



The side of the plate with the nerve-endings has been shown 

 to be negative to the other side, and the current passes from the 

 upper (positive) surface of the whole organ to the lower 

 (negative). 



In the Electric Eel [Electrophorus) there are two organs on 

 each side of the tail, a large upper one and a small lower one 

 along the base of the anal fin (Fig. 60c). Their structure is 

 the same as those of the Torpedo, but the columns containing 



