ELECTUICAL OUGANS IN FISHES. 2'J3 



The posterior of these is a delicate, wide-meslied, iibrous hiyer, 

 in wliicli alone the nerves ramify ; the anterior consists of 

 a thicker layer (»f tlie peculiar vascular, dotted, nucleated 

 texturu which forms the laminie in Torpedo. Both surfaces 

 of the vasculo-cellular layer present an arrangement of i)ro- 

 minent, close-set, undulating ridges, with thick, rounded, 

 nucleated margins. The ridges are more fully developed on 

 the anterior than on the posterior surface of the layer, and 

 from tlie ridges of the latter a number of thread-like pro- 

 longations pass backwards through the interposed lluid to the 

 fibro-nervous layer, so as to connect the two layers as one 

 compound lamina. From the measurements and calculations 

 of Pacini, the superficial extent of the anterior surface of the 

 vasculo-uucleated layer is increased by this rigid structure 

 from five to sbc times, the posterior about twice. 



The electro-motor series, therefore, in Gymnotus, instead 

 of simple laminre, as in Torpedo, consist of compound laminie 

 separated by layers of fluid. There are thus two kinds of 

 fluid in the electro-motor series of Gymnotus — fii-stly, that 

 between the vasculo-cellular layers and the fibro-nervous, 

 and which must be considered as an element of each com- 

 pound electric diaphragm ; and, secondly, that between any 

 two electric diaphragms, which is the homologue of the fluid 

 layer in Toq^edo. 



As the current in Gpnnotus passes from before backwards, 

 Pacini denominates the vasculo-cellular layer the positive, and 

 the fibro-nervous layer the negative element, of the electro- 

 motor seriea 



Tlie batteries in ^ralaptenmis are two in number, sepa- 

 rated, but at the same time intimately connected to one another 

 in the mesial plane, along the dorsal and ventral margins of 

 the body, so as to form a continue tus layer of a gelatinous 

 consistence, closely adherent to the skin, and enclosing as in a 

 sac the entire animal, except the head and fins. In the 



