ELECTRICAL ORGANS IN FISHES. 289 



XV. ON THE ELECTEICAL APPAEATUS IN TOE- 

 PEDO, GYMNOTUS, MALAPTEEUEUS, AND EAIA. 



THE electrical apparatus in fish consists of three parts the 

 battery, the nervous centre, and the internuncial cord. 



The following would appear to be the general expression 

 for the structure of the battery a very large number of 

 laminse, consisting of vascular nucleated texture, largely sup- 

 plied with centrifugal nerve-fibres, distributed on one of their 

 surfaces only ; so arranged in reference to one another, and to 

 thin intervening layers of fluid, as to constitute a uniform 

 series, in the order : nerve-surface cellulo-vascular surface 

 fluid, nerve-surface cellulo-vascular surface fluid, etc. etc. 



The nervous centre consists of a portion of the cerebro- 

 spinal axis developed in relation to the large nerves distributed 

 to the battery ; and so organised, as to be capable, not only 

 of excito-motory action, but also of being subjected to the 

 influence of the will 



The internuncial cord is a centrifugal nerve, connected at 

 one extremity to the nervous centre of the apparatus, and at 

 the other distributed on the nervous surfaces of the lamina 

 of the battery. 



In Torpedo there are two batteries which occupy the two 

 spaces between the pectoral fins, the head, and gills. Each 

 battery consists of a number of hexagonal, pentagonal, or 

 tetragonal prisms, which vary in number from 400 to up- 

 wards of 1000, according to the age of the animal. The prisms 

 extend perpendicularly between the dorsal and abdominal in- 

 tegument ; and are separated from and connected to it by a 



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