VOL. LXIII.] PHILOSOPHICAL TRANSACTIONS- 481 



1st and 2d openings, and, after furnishing it with small branches, passes into the 

 organ near its middle. The 3d trunk, after leaving the skull, divides into 2 

 branches, which pass to the electric organ through the gills; one between the 2d 

 and 3d openings, the other between the 3d and 4th, giving small branches to 

 the gill itself. These nerves, having entered the organs, ramify in every 

 direction, between the columns, and send in small branches, on each partition, 

 where they are lost. 



The magnitude and the number of the nerves bestowed on these organs, in 

 proportion to their size, must on reflection appear as extraordinary as the phe- 

 nomena they afford. Nerves are given to parts either for sensation or action. 

 Now if we except the more important senses of seeing, hearing, smelling, and 

 tasting, which do not belong to the electric organs, there is no part, even of the 

 most perfect animal, which, in proportion to its size, is so liberally supplied 

 with nerves; nor do the nerves seem necessary for any sensation which can be 

 supposed to belong to the electric organs. And with respect to action, there is 

 no part of any animal, with which I am acquainted, however strong and constant 

 its natural actions may be, which has so great proportion of nerves. If it be 

 then probable, that those nerves are not necessary for the purposes of sensation, 

 or action, may we not conclude that they are subservient to the formation, 

 •collection, or management of the electric fluid; especially as it appears evident, 

 from Mr. Walsh's experiments, that the will of the animal does absolutely 

 control the electric powers of its body; which must depend on the energy of 

 the nerves. How far this may be connected with the power of the nerves in 

 general, or how far it may lead to an explanation of their operations, time and 

 future discoveries alone can fully determine. 



jIn Explanation of the Engraving of the Torpedo. 



PI. 9, fig. 4, Tlie upper surface of the electric organ. — aa. The common skin of the animal. 



B, The inspiratory opening. — c. The eye.— d. The part in which the gills are inclosed. — eeb, Th« 

 skin dissected oft' from the electric organ, and turned outwards; tlie honeycomb appearance on its 

 internal surface corresponding witli the upper surface of the organ.— f. The part of the skin which 

 covered the gills, with some ramifications of an excretory duct on it. — ggc. The upper surface of 

 the electric organ, formed by the upper extremities of the perpendicular columns. 



Fig. 5, The right electric organ, divided horizontally into nearly 2 equal parts, at the place wher« 

 the nerves enter; the upper half being turned outwards. — a a, bb, cc, dd. The corresponding 

 parts of the trunks of the nerves, as they emerge from the gills, and ramify in the electric organ. — 

 AA, The Istor anterior tixink arising just before the gills. — bb, The 2d or middle trunk arising 

 behind the ist gill. — cc. The anterior branch of the 3d trunk arising behind the 2d gill.— dd. The 

 posterior branch of tlic 3d trunk arising behind the 3d gill. 



Fig. 6, A perpendicular section of the torpedo a little below its inspiratory openings. — a a, The upper 



surface of the fish. — bb. The muscles of the back, as divided by the section. — c. The medulla spinalis. 



D, The oesophagus. — e. The left gill split, to expose the course of a tmnk of the nerve through it.— 



r. The breathing surface of die right gill. — go, The fins. — uii. The perpendicular columns which 



VOL. XITI. 3 Q. 



