xr 



ELECTRICAL FISHES 



369 



standing its eel-like shape, the body-cavity occupies but a small 

 part (not quite one-fifth, including the head) of the total length, 

 while the four electrical organs fill up the space that would other- 

 wise be devoted to the abdomen (C. Sachs). As seen from above, 

 the trunk of the fish appears to taper off behind like the blade of 

 a knife. The gymnotus, in comparison with other electrical 

 fishes, reaches a considerable size (according to Sachs the length 

 may be 155 cm., or 170 cm. according to v. Humboldt), while 

 the species of torpedo most common 

 in Europe measures, at most, 2030 

 cm., rarely 70 cm. The electric ray 

 peculiar to the coast of Eastern 

 America (T. occidentalis, Storer) is 

 the sole species that becomes double 

 this size under certain conditions, 

 and may be defined as the largest 

 and heaviest, if not the longest, of 

 all the electrical fishes (Fritsch). 



As seen in a transverse section 

 of Gymnotus (Fig. 238), the body 

 consists mainly on the farther side 

 of the head and body-cavity, of a 

 gelatinous, transparent mass, which 

 forms on each side a large, and a 

 second much smaller accumulation, 

 situated below. These are separated 

 by a layer traversed by muscle-fibres, FIG. 233. T.S. through trunk of Gym- 



-iv i T> T> i j_i notus. gO = great organ; fcO = small 



termed by du BoiS-KeyniOnd the organ; Z m= intermediate muscular 



" intermediate muscular layer," and 



viewed by Fritsch as a vestige of the muscles whose transforma- 



tion gave rise to the greater organs (Fig. 238). 



Closer inspection proves the substance of the organ to be 

 penetrated by parallel walls of connective tissue, lying one 

 above the other, and running, in transverse section, from a 

 middle, vertical septum to the external circumference of the 

 body. These " longitudinal partition walls," which (as shown 

 by the lateral aspect, Fig. 239) extend throughout the entire 

 length of the organ, including the intermediate muscular layer, 

 serve to bound shallow spaces lying in horizontal strata, each of 

 which, with its content, corresponds to a column of the Torpedo 



VOL. II 2 B 



