LOWER VERTEBRATES. 



fluid. The nervous supply is very large, the nerves which run to the organs being 

 enormously developed. Each organ receives one branch of the trigeminal, and four 

 branches of the vagi\s, ncr\es. Tlie number of prisms is very large, nearly five hun- 

 dred having been counted in a single organ. These electric organs have been exten- 

 sively studied, and the evidence goes to show that they are composed of extremely 

 modified muscles. This is shown not only by their anatomy and development, but by 

 their physiological action. Says Dr. Gilnther : — 



Fig. 64. — Raia batis, common European skate, and Karcacion 7na}^moi'ata, spotted torpedo. 



"The phenomena attending the exercise of this extraordinary f.aculty also closely 

 resemble muscular action. The time and strength of the discharge are entu-ely under 

 control of the fish. The power is exhausted after some time, and it needs repose and 

 nourishment to restore it. If the electric nerves are cut, and divided from the brain, 

 the cerebral action is interrujited, and no irritant to the body has any effect to excite 

 electric discharge; but if their ends be irritated, the discharge takes place, just as a 

 muscle is excited to contraction under similar circumstances. And, singularly enough, 



