ELECTRICAL 0R0.1NS IN FISHES. 201 



forming meshes. Pacini {loc. cit) lias lately made a most 

 important addition to "Wagner's description of llie lamina*. 

 The laminie, or electrical diaphragms, as Pacini terms them, 

 are attached, as has been already stated, by their angles only. 

 The vessels and nerves enter at these points, but so as to be 

 at first placed on the under surface of the diaphragm, and there- 

 fore in the fluid intcrpo.sed between that surface and the upper 

 surface of the diaphragm below. Passing inwards and ramify- 

 ing in this fluid, they ultimately pass up to the luider surface, 

 and the nerves are distributed on thai surface only of the <lia- 

 phragm to which they belong. Now, as the dorsal surface in 

 Torpedo is positive and the abdominal surface negative, it 

 follows, as Pacini has indicated that the upper surface of eacli 

 electrical diaphragm, consisting only of soft, dotted, nucleated 

 vascular texture, is positive, while the under surface, on which 

 the nerves only ramify, is negative. 



Pacini was led to the observation of the position of the 

 nerves in the electrical diaphragms of Torpedo, by the more 

 complex structure which he had previously discovered in the 

 corresponding parts of Gymnotus. 



Gymnotus possesses four batteries, which extend nearly 

 the whole length of its eel-like body, from behind the pectoral 

 fins to the extremity of the tail ; forcing the lateral muscles 

 towards the dorsal, and the comparatively small abdominal 

 viscera, with the anus, towards the cephalic region. The great 

 or dorsal batteries are separated from one another above by 

 the vertebral column, the great vessels, the displaced lateral 

 muscles, and the air-bladder ; below by a mesial aponeurotic 

 septum, along which the nerves pass to the batteries and 

 ventral fin. Laterally these dorsal batteries are intimately 

 connected to the skin ; and inferiorly are separated fn»m thf 

 ventral, or small batteries, by a thin layer of muscle. Tlie 

 small batteries are, moreover, separated fmm the skin by tlie 

 laterally-dis])laced muscles of the ventral fin ; but are inti- 



