ELECTUICAL ORGANS IN FISHES. 289 



XV.— OX Tin-: klkctiucal ArrAUATUs in tor- 

 pedo, GYMNOTUS, ]\L\XAPTEltUIiUS, AXD PAIA. 



The electrical apparatu.s in fish consists of three parts — the 

 batteiy, the nervous centre, and the internuncial cortL 



The followinL,' Mould ap[)ear to be the general expression 

 for the structure of the batteiy — a very larj,'e number of 

 larainji', consisting of vascular nucleated texture, largely sup- 

 ])lied with centrifugal nerve-fibres, distributed on one of their 

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

 thill intervening layers of fluid, as to constitute a unifonn 

 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 nerv^e, connected at 

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

 the other distributed on the nervous surfaces of the laminae 

 of the battery. 



In Torpedo there are two batteries which occupy the two 

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

 batteiy consists of a number of hexagonal, i)cntagonal, or 

 tetragonal prisms, which vary in number from 400 to ui>- 

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

 extend ])crpendicularly between the dorsal and abdominal in- 

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



u 



