88 



ANIMAL ELECTRICITY. 



with their large nerves, are the sole means 

 employed in bringing this mysterious agent 

 under the control of the animal's volition. 

 They are therefore well worthy of an attentive 

 examination. 



i. The electrical organs in the torpedo. 

 The torpedo is a flat fish, possessing the same 

 general appearance and structure as the rays, 

 and classed along with them in zoological sys- 

 tems. The electrical organs occupy a large 



coverings are discovered investing the electrical 

 organs. The outer one has longitudinal fibres, 

 which are rather loosely adherent, and, around 

 the margins of the organs, seem to inosculate 

 with the skin. The inner fascia is of consider- 

 able density, forms the immediate tunic of the 

 electric columns, and sends processes down 

 between them to form their partitions. Through- 

 out their whole extent, the essential part of the 

 electrical organs is formed by a whitish soft 



Fig. 47. 



Upper surface of electrical organ of left side. 



A, common integuments. B, branchial opening. C, eye. 

 sected off from the electrical organ, and turned outwards. 

 G G, the upper surface of electrical organ. 



D, situation of the gills. E E, skin dis- 

 F, part of the skin which covered the gills. 



part of the broad expansions of the body, 

 which in the other allied fishes are formed 

 only by the lateral fins. They form two sepa- 

 rate masses, one on either side of the head and 

 gills, extending outwardly to the cartilaginous 

 margins of the great fins; and, posteriorly, to 

 the cartilage which separates the thoracic from 

 the abdominal cavity. Their form and the 

 honey-comb embossments of their surfaces can 

 be distinguished through the skin both of the 

 dorsal and ventral aspects. The common inte- 

 guments being removed, two strong fascial 



pulp, divided into numerous pentagonal prisms 

 by the fascial processes just mentioned. These 

 lie close together, parallel with one another, 

 and perpendicularly between the dorsal and 

 ventral surfaces of the fish, so that their extre- 

 mities are separated from these surfaces only 

 by their fascial and the common integuments. 

 When these are removed, the columns present 

 something of the appearance of a honey-comb. 

 The columns are longest next to the head and 

 gills, and thence gradually diminish outwardly, 

 until, on the external margin, they are only 



