PRODUCTION OF ELECTRICITY 433 



order of Soft-finned Fishes (Malacopterygii) and living in the 

 Nile, Congo, and other rivers of sub-tropical Africa, there are two 

 electric organs situated, as in Gymnotus, on either side of the tail, 

 but of much less power. These fishes have a curious appear- 

 ance on account of the shape of the head, which though differing 

 much in the various species, is always more or less unlike that 

 of a typical fish. In many species the snout is much elongated 

 and bent in various ways, so that some resemblance to different 

 mammals and birds is produced ; thus one species suggests an 

 elephant, another a horse, another a sheep, another a plover, 

 another an ibis, etc. The mouth is always small, and in the 

 species in which the snout is most elongated is reduced to a very 

 minute aperture. In accordance with this the food consists of 

 minute animals such as insect-larvae and fresh-water Crustacea, 

 fragments of leaves and other vegetable matter. Professor 

 Fritsch, who investigated the electric organs of these fishes in 

 Egypt, states that they are, in contrast to other electric fishes, 

 very active and excitable, and he found it very difficult to keep 

 them alive in captivity. The electric powers of these fishes 

 are very weak, and were formerly denied altogether ; they seem 

 to be of use only as a protection of the fish against enemies. 



The last of the electric fishes 1 is the electric cat-fish Malop- 

 ternrus electricus, one of the Siluridae and therefore belonging, 

 like Gymnotus, to the sub-order Ostariophysi. It is a curious 

 fact that whereas in Torpedinidae and Mormyridae the electric 

 organs are characteristic of the whole family they are confined 

 in Gymnotus to a single genus and in Malopterurus to a single 

 species. The electric cat-fish is also an inhabitant of Africa, 

 occurring in all the large rivers of the tropical parts of that 

 continent and extending to the lower Nile ; it grows to a length 

 of 3 ft. It is sluggish in its movements and lurks in dark 

 places. Its flesh is used as food. 



In structure the electric organs of all these fishes, with the 

 exception of Malopterurus, are closely similar. Each organ 

 consists of a number of columns of somewhat gelatinous tissue, 

 lying parallel to one another and side by side, the surfaces in 

 contact being somewhat flattened. These columns are sepa- 

 rated by fibrous tissue, they run vertically in Torpedo, longitu- 

 dinally in the other cases. Each column consists of a number 



1 See note, page 440. 

 28 



