Torpedo, Gymnolus eh^ricus and Silurus eleSlr'icus. 1 29 



rnake before they are inferted in the fkiri. Thefe long tubes 

 ieem to be of the fame nature as thoi'e of the torpedo, and 

 contain a gelatinous and albuminous fubltance entirely fimi- 

 lar. Hitherto we obferve in this refpeil no other differences 

 between the common rays and the torpedo, except that the 

 tubes in the latter are very fliort, vertical, clofe to each other, 

 and parallel ; while in the other rays they are much longer, 

 bend around the principal mufcles of the ele6lric machine-;, 

 and divide into feveral 'bundles formed of divergent radii. 



But if thefe organs do not vary in each fpecies birt bv a 

 different arrangement of parts, is it not to be apprehended 

 that we may fall into a confequence contrary to the fafts ob- 

 fcrved, and ought we not to fuppofe that all rays are more, 

 or lefa endowed with the electric properties of the torpedo? 

 Such, indeed, would be the opinion which we ought to form, 

 if thefe organs were not diftinguilhed by a character on whiclj 

 depend, in part, the artonifliing properties of the torpedo. 

 The tubes in the common rays open on the outfide of the 

 Ikin by orifices peculiar to them, and are fo many excretory 

 organs of the gelatinous matter v.hich they contain. In the 

 torpedo all thefe tubes are completely Cxut, not only by the 

 fkin, which has no perforations, but alfo bv aponeurofes which 

 extend over the whole furface of the eleflric f^rgan. As the 

 gelatinous matter cannot then efcape, it is forced to be accu- 

 mulated in thefe tubes : hence, no doubt, the greatnefs of 

 their diameter, and on this account alfo their number in- 

 creafes at the different periods of life. Vald and Hunter, 

 indeed, found this progrcffive augmentation. They counted 

 more than two hundred of thefe tubes in yninig fubjefls, 

 from four to five hundred in adult torpedoes, and even twelve 

 hundred in an individual of a large fize. 



It is to John Hunter, as alreadv faid, that we are indebted 

 for the befi: dcfcription of the ele6lric organs of the torpedo*. 

 iMonro, in his Phyfiology of Fiflics, has alfo defcribed the 

 correfponding apjjaratus found in the other rays; but I flatter 

 niyfcif that I am the firll who corpparcd thefe organs, who 

 proved their identity, and reduced them to the fame fyltein 

 of organization. The elc6lric organ of the torpedo is really 

 an organ of touching, furnidied with an ap^iaratus as extcn- 

 -ve as that of feeing or fmelling. The ne'rves which pro- 

 - ':ed tliitlier are fo large that their volume appeared to i Junter 



- extraordinaiy as the phaenomena to which they give rife, 

 1 hey fuddenly expand in a gelatinous mucus, and nothing 



aipedes their free conimunlvalion with external bodies. 



♦ Phil(jrotihii:4 TranfuTtions 17/3: ^. 4!*;. 

 Vt>T.XV. N0.58. K There 



