290 ELECTRICAL ORGANS IN FISHES. 



thin but dense aponeurosis, which at the same time separates 

 them all from, and connects them to one another, by passing 

 inwards in single layers, so as to form a continuous series of 

 prismatic aponeurotic compartments, in the interior of which 

 the prisms are situated. Each prism consists of delicate, 

 horizontal, superimposed laminae, separated from one another 

 by thin layers of fluid, so that the arrangement bears a general 

 resemblance to a galvanic pile. It has hitherto been supposed 

 that the laminae are connected by their margins to the 

 aponeurotic wall which surrounds the prism ; but Pacini 

 (Sulla struttura intima dell organo elettrico del Gimnoto, e di 

 altri pesci elettrici, 1852) has lately shown that the laminae 

 are attached by their angles only to the comers of their apo- 

 neurotic sheaths ; and that an entire pile may be removed from 

 its containing cavity, by cutting the four, five, or six series of 

 attachments by which it is fixed. It is extremely important 

 that the structure of the laminae should be determined. 

 Valentin ("Electricitat der Thiere," mW&gnQT'sffandwdrterluch 

 der Physiologie) states, that each lamina consists of a thin 

 prolongation of the aponeurotic wall of the pile, covered above 

 and below by an epithelial layer, and affording a matrix for 

 the ultimate divisions of the vessels and nerves, which, he is 

 inclined to believe, are so arranged, that the terminal nervous 

 plexuses are placed towards the upper, the capillaries towards 

 the lower surface. Savi (Matteucci and Savi, Traitt des 

 Phenom&nes Electro-Physiologiques, 1844) describes the ele- 

 mentary filaments of the nerves as forming a network by 

 anastomosis in the lamina ; but Eudolph Wagner (Annales 

 des Sciences Naturelles, 1847) has shown that each elementary 

 filament, enveloped in a very thick sheath, divides at once 

 into twelve to twenty-five secondary filaments, which, passing 

 towards the laminae, splitting into two or three ternary fila- 

 ments and losing their envelopes and dark contours, disappear 

 in the soft, dotted, nucleated substance of the laminae, without 



