ELECTRIC ORGANS. 



127 



called " electric-' or " end-plates." These can be summarily 

 described, as they are essentially the same in all electric Fishes. 



After the nerve, running in the septum between the compart- 

 ments, has by degrees lost its thick sheath and thus has almost 

 ceased to show a double contour, it suddenly gives rise to a club- 

 shaped swelling, and then divides up into a number of primitive 

 fibres, which branch out in a tree-like manner, without, however, 

 giving rise to definite meshes, so that we cannot speak of a proper 

 nervous network. In Torpedo the nerve spreads out on the ventral 

 side of the structure known as an electric plate (Fig. 103, EP\ 

 while in Gynmotus it passes to the posterior surface, that is to the 

 one turned towards the tail. Finally in Malapterurus, the nerve, 

 as in Gymnotus, passes on to the posterior surface of the electric 

 plate ; it does not stop here, however, but perforates the plate, so 



&<&&. 



/T 



301 



W ^r-.. T~~- :. '-.-*^J=- r ^f=^-- - . 



^JW^^ 



tjzrJ&. 



Jr 



I 



tfio. 103 SECTION THROUGH THE ELECTRIC CHAMBERS. (Greatly enlarged, and 



semidiagrammatic. ) 



BG, framework of connective-tissue, forming walls of compartments ; EP, electric 

 plates ; N, nerves entering into the septa between the compartments ; NN, 

 terminal fibres of the nerve, passing to the posterior (Gymnotus) or under (Torpedo) 

 surface of each compartment ; G, gelatinous tissue ; the arrow points towards 

 the head (Gymnotus), or towards the dorsal side of the animal (Torpedo). 



as to spread out on the anterior surface, turned towards the head. 1 

 This difference must be borne in mind on account of the direction 

 taken by the electric current, to be described later on. 



Each electric plate consists of a homogeneous disk, transparent 

 in the fresh condition, and surrounded by a special membrane, 

 within which star-like cells with long processes are present. Both 

 surfaces of the plate exhibit irregular protuberances, separated 

 from one another by shallower or deeper notches, and giving the 

 whole an irregular appearance. 



1 Babuchin, who had the opportunity of examining Malapterurus in the fresh 

 condition, disputes strongly the. perforation of the plate by the nerve ; whether 

 rightly or not, new researches must show. 



