114 Professor Francis Gotch [March 17, 



WEEKLY EVENING MEETING, 

 Friday, March 17, 1899. 



Sir James Oeichton-Beowne, M.D. LL.D. F.R.S., Treasurer and 

 Vice-President, in the Chair. 



Professor Francis Gotoh, M.A. F.R.S. 



The Electric Fish of the Nile. 



The lecture dealt almost exclusively with the formidable fish found 

 in the rivers of North and of West Africa, Malapterurus electricus. 



Photographs were shown of the drawings upon the interior of the 

 tomb of Ti, showing that the fish was recognised as remarkable by the 

 Egyptians five thousand years before the Christian era. Living 

 specimens of the fish were also displayed, these having been given to 

 the lecturer, for the purpose of illustrating the lecture, by the authori- 

 ties of the Liverpool Corporation Museum. 



The structure of the electrical organ was then described. It is 

 situated in the skin enclosing the whole body of the fish, and has a 

 beautiful and characteristic appearance when seen in microscopio 

 sections. Each organ consists of rows of compartments, and each 

 compartment has slung athwart it a peculiar protoplasmic diso 

 shaped like a peltate leaf, with a projecting stalk on its caudal side. 

 Nerves enter each compartment, and end, according to the recent work 

 of Ballowitz, in the stalk of each disc. By these nerves nervous 

 impulses can reach the organ ; the arrival of such impulses at the 

 nerve terminations evokes a state of activity which is associated with 

 the development of electromotive charges of considerable intensity 

 constituting the organ shock. The shock is an intense current travers- 

 ing the whole organ from head to tail and returning through the sur- 

 roundings ; it stuns small fish in the neighbourhood and can be felt 

 by man when the hand is placed near the fish, as a smart shock reaching 

 up the arms to the shoulders. 



Recent investigations made by the lecturer at Oxford in conjunc- 

 tion with Mr. G. J. Burch were next described. These comprised 

 a large series of photographic records of the displacement of the 

 mercury of a capillary electrometer in consequence of the electrical 

 disturbance in the organ which is " the organ shock." A number of 

 these records were exhibited ; they showed the time relations, mode 

 of commencement and manner of subsidence of the shock, and demon- 

 strated its similarity to the electrical changes known to exist in 

 nervous tissue during the passage of a nervous impulse. A remark- 

 able feature of the organ shock as distinct from the phenomena of 



