ELECTEICAL ORGANS IN FISHES. 297 



js of the Royal Soc. Edin. Dec. 1844). As Dr. Stork's 

 description did not involve a sufficient account of the micro- 

 scopic structure, which, in the absence of direct experimental 

 evidence, could alone afford the basis of a legitimate hypo- 

 thesis as to the function of the organ, I at the time under- 

 took that inquiry, and stated the results in a paper read at a 

 subsequent meeting of the Society.* In this paper the pre- 

 sumed electrical organ was described as consisting of antero- 

 posterior, or linearly-arranged series of compressed chambers, 

 lined by a nucleated gelatinous vascular substance ; and sus- 

 pended in the cavities of the chambers numerous sling-like 

 anastomosing ultimate doubk contour nerve-tubes, with the 

 centre of each loop occupied by a nucleus. There was 

 also described a peculiar undulating ridge-structure (the 

 alveoli of Eobin), somewhat similar to the grooved and pitted 

 marking on the dermal plates of certain fossil fishes ; but the 

 relations of this structure to the nucleated gelatinous texture 

 were not determined ; although its probable importance was 

 indicated as a characteristic feature in an organ which could 

 only be referred to electrical structures. 



The entire structure of the presumed electrical apparatus 

 in the rays, has, since Dr. Stark's discovery, been redis- 

 covered, and most minutely and accurately described by 

 Eobin (An. des Sci. Nat. 1847) ; and from his descriptions, 

 as verified by myself, the account in this lecture has been 

 derived. 



As the four nerves distributed to each battery of Torpedo 

 are branches of the fifth and eighth cerebral pairs, the nervous 

 centre of its electrical apparatus is situated in the medulla 



* This paper was read before the Royal Society of Edinburgh, 6th January 

 1845 ; but its title only is recorded in the Proceedings of that day. In a 

 manuscript found amongst his papers, he states that he was then engaged in 

 observations on the structure of the electrical organs of two of the electrical 

 fishes (torpedo and gymnotus), made during dissections for the University 

 collection. EDS. 



