66 



ELEMENTARY LESSONS ON [CHAP. i. 



68. Animal Electricity. Several species of crea- 

 tures inhabiting the water have the power of producing 

 electric discharges by certain portions of their organism. 

 The best known of these are the Torpedo^ the Gym- 

 notus, and the Silurus, found in the Nile and the 

 Niger. The Raia Torpedo, 1 or electric ray, of which 

 there are three species in- 

 habiting the Mediterranean 

 and Atlantic, is provided with 

 an electric organ on the back 

 of its head, as shown in Fig. 

 37. This organ consists of 

 laminae composed of polygonal 

 cells to the number of 800 or 

 1000, or more, supplied with 

 four large bundles of nerve 

 fibres ; the under surface of 

 the fish is - , the upper + . 

 In the G-ymnotus electricus, 

 or Surinam eel (Fig. 38), the 

 electric organ goes the whole 

 length of the body along both 

 sides. It is able to give a 

 most terrible shock, and is a 

 formidable antagonist when if 

 has attained its full length of 

 5 or 6 feet. Humboldt gives 

 a lively account of the combats 

 between the electric eels and 

 the wild horses, driven by the 

 natives into the swamps in- 

 habited by the Gymnotus. 



Fig. 37- 



Nobili, Matteucci, and others, have shown that nerve- 



1 It is a curious point that the Arabian name for the torpedo, ra-ad, 

 signifies lightning. This is perhaps not so curious as that the Electro, of 

 the Homeric legends should possess certain qualities that would tend to 

 suggest that she is a personification of the lightning. The resemblance 

 between the names electro, and electron (amber) cannot be accidental. 



