Electric Organs. 527 



closed tube in which the animal is concealed, its head and tail, as it 

 were, alone projecting. The separate plates of which the organ con- 

 sists, are arranged horizontally in the Torpedo, vertically in the Gymno- 

 tus. Each of these plates consists of an extremely delicate membrane, 

 which, when the organ is in a state of activity, exhibits positive elec- 

 tricity on one side and negative on the other. The currents of the nu- 

 merous plates combine, as in a battery, and thus all together afford a 

 very powerful current. With each plate is connected a nerve fibre, by 

 means of which the animal is capable of voluntarily effecting the elec- 

 tric discharge, just as voluntary muscular contractions can be effected 

 by means of the nerve. These nerves may also be artificially irritated, 

 with the result of producing one or more electric shocks, just as irrita- 



FIG. 252. Torpedo (Electric ray). Shoiving Electric Organs. (Gegenbauer.) 



On the right is shown the dorsal surface of the electric organ, on the left the nerves 

 which go to it are shown. 



E 0. Electric organ. Le Electric lobe of the brain. 



Br Gills on the right they are covered Gr. Gelatinous tubes of the skin (sense 



by their muscular layer. canals ). 



Tr. Trigeminuin, or 5th nerve. V Vagus, or pneumogastric nerve. 



O Eye. 



tion of a motor nerve elicits one or more muscular contractions. The 

 analogy of electric organs and of muscle is, in fact, from a physiolog- 

 ical point of view, complete." (Rosenthal.) 



