iqo Coniparatii'e Anatomy of the EleBric Organs of the 



There can be no doubt that they perform a very confiderable 

 part in the elc6tric phaenoinena. Hunter was of opinion that 

 they are deftincd to form, collcft, and dire£l the nervous 

 fluid. Their influence however is proved, fince it is known 

 that the concurrence of the will of the animal is indifpen- 

 fably neceffarv for giving (liocks. This evidently refults from 

 the obfervati'ons of MrValll, and from thofe which I had 

 occafion to repeat myfelf. 



However, (ince thefe nerves are found in other rays diftri- 

 buted nearlv in the fame manner as in the torpedo, it muft 

 be allowed that they are not alone fufficient for the produc- 

 tion of cletlricitv, and that for this purpole they muft alio 

 be in a certain relation with the furrounding parts. Do the 

 apertures of the tubes in the rays favour the ilfiie of the 

 nervous fluid ? Or, as in the torpedo, do the nerves require 

 a larger quantity of gelatinous fubftance to enable them to 

 expand in numerous rami, and to become proper for acting 

 with more fucrgy ? 



In order ihat'we may afcertain how far thefe conjeftures 

 mav be founded in truth, let us compare the eleftric organs 

 of the torpedo, thofe defcribed bv Hunter in the gj'vinotus 

 ele£lricus, and thole which I difcovered in the Jilurus ele£in- 

 cus. Thefe two fiflies arc fo different from the torpedo, that 

 they afford realon to hope that this compariion will throw 

 confiderable light on the prelent quedion. 



The gymnotus belongs to that order of filhes diftinguiflied 

 by the name of apoda : it is the genus which approaches 

 neareft to that of the murencs and eels ; confequcntly they 

 have a very long body, almoft cylindric, and fimilar to that 

 of ferpents.' Separated from the murente becaufe they have 

 no fins on the back or tail, they arc diftinguiflied from them 

 alfo by the great Ihortuefs of the abdomen. The anus, in- 

 deed, is lb near the head that it opens before the peroral 

 fins. But, on the other hand, the gymnoti have the tail of 

 a moft extiaordinarv length : it is an organ to which all the 

 reft; I'eeni to have been facrificed, and it is rendered lighter 

 by adifpofnion peculiar to this kind of fifh. The air-bladder, 

 inftead of being iuclofcd in the abdominal cavity,- extends to 

 the infidc of the tail, and is continued to its extremity. It 

 is above this bladder that there is found in the gymnotus 

 electricus a very Angular apparatus ftill more attonifliing by 

 its enormous fize than by it> llrufture ; an apparatus of which 

 there is no vefcige in the other Ipccies of this genus, and 

 which may be eafily known to be the ele6lric organ of the 

 gymnotus. 

 ' This or2:an is formed by the union of a very ercat number 



of 



