ELECTEIC OKGANS OF FISHES. 



355 



234 



Section of ilalapterurus electricus. ccxix. 



to the fore part of the enormous batteries ; for the digestive and 

 generative viscera, with the respiratory and circulating organs, 

 the brain and organs of sense, — 

 all, in fact, that constitute the 

 proper animal, — are confined to 

 that small segment of the entire 

 body which is anterior to the elec- 

 trical apparatus, fig. 232, b. The 

 vent even opens beneath the head, 

 in advance of the pectoral fins. 



The electric organs of the Ma- 

 lapterurus electricus 1 form a layer 

 fig. 234, a, immediately beneath 

 the skin, enveloping the whole 

 body except the head and fins, and separated from the muscles, 

 ib. G, by a fascia with vessels and nerves, ib. b, and by a layer 

 of adipose tissue, ib. E. The electric organ is divided by fine 

 decussating membranes into minute lozenge-shaped cells, about a 

 third of a line in diameter, fig. 235, b. It is supplied by a large 

 nerve issuing from the beginning of the myelon and arising from 

 a mass, in its substance, of ganglion-cells, like those in the electric 

 lobes of the Torpedo. A considerable ganglion is also formed upon 

 the nerve beyond its origin, from which the trunk is continued 

 along the side of the body, like a ' nervus lateralis,' and distributes 

 branches to the diffused organ. The structure of the organ is such 

 that the electric currents run in all directions, and 

 a discharge would take place from any point of 

 its surface, whence, perhaps, the necessity for a 

 layer of nonconducting substance, E, between 

 the proper body of the fish and the organ. The 

 shock delivered, wanting the concentration re- 

 sulting from the structure in the Torpedo, is 

 comparatively feeble, but suffices for defence; 

 the fish being protected by its electrifying coat, 

 as is the hedgehog by its spines. 



In the Mormyrus longipinnis the electric organ 

 consists of four series of membranous septa 

 placed longitudinally on the tail, two on each 

 side. Each series consists of about 150 septa 

 with intervals of ^th of a line, filled by albu- 

 minous fluid. The septa are stronger than 

 those in the hexagonal columns of the Torpedo. 2 



235 



E DC 



Section of electric organ, 

 Malapterurus, ccxviij. 

 a, skin ; b, electric cells 

 c, fascia ; D, cellular tis- 

 sue, with a, artery, v, 

 vein, h, nerve; E, adi- 

 pose tissue. 



1 xcii. and ccxix. 



ccxx. 





A A 2 



