ELECTRTC ORGANS 



191 



A 



side an upper and lower row of electric organs. In addition to the 

 Fishes here referred to, electric organs have also been described 

 in other Teleosts (e.g. Astroscopus). 



With the possible exception of Malopterurus, in which the 

 electric apparatus is said to be derived from the epiderm, the 

 electric organs of Fishes 

 consist of metamor- 

 phosed striated muscu- 

 lar fibres, and the nerve- 

 endings belonging to 

 them are the homo- 

 logues of the motor end- 

 plates which are ordin- 

 arily found on muscles. 



As regards the struc- 

 ture of the electric 

 organs, the same essen- 

 tial arrangements are 

 met with in all. The 

 framework is formed of 

 fibrous tissue enclosing 

 numerous cells, which, 

 running partly longi- 

 tudinally, partly trans- 

 versely through the 

 organ, gives rfse to 

 numerous polygonal or 

 more or less rounded 

 chambers or compart- 

 ments. These latter are 

 arranged in rows, either FIG. 143, A and B. THE ELECTRIC ORGAN OF 

 along the longitudinal Gynmo/ux elu-trim*. (B, from a preparation by 



axis of the body (Gym- 



notus, Malopterurus) or A, anus ; DM, DM 1 , dorsal portions of the great 



Ff 



lateral muscles, seen partly in transverse, partly 

 in longitudinal, section ; E, the electric organ, 

 seen in transverse section at E (B), and from 

 the side at E 1 ; Ft, fin ; H, skin ; LH, posterior 

 end of body-cavity ; Sep, median longitudinal 

 fibrous septum between the left and right 

 electric organ and lateral trunk-muscles ; VJ\I, 

 VM 1 , ventral portions of the great lateral 

 muscles, seen partly in transverse, partly in 

 longitudinal, section ; WS, vertebral column 

 from the side, showing the spinal nerves, and 

 in transverse section. 



iii a dorso-ventral direc- 

 tion (Torpedo), forming 

 definite prismatic col- 

 umns (Fig. 144). The 

 compartments are filled 

 with a homogeneous 

 fluid or semi-fluid sub- 

 stance, the nature of 

 which is not thoroughly 

 understood. It is known 



to correspond to modified muscle-substance, and it contains 

 numerous large, round and oval nuclei, as well as certain highly 

 refracting bodies. 



Numerous vessels and nerves ramify in the connective tissue 



