408 ELECTRO-PHYSIOLOGY CHAP. 



blocked by the introduction of gold-leaf or tinfoil, between the 

 primary contracting muscle and the nerve of the secondary pre- 

 paration (cf. I. p. 361). 



The effects of shock from Torpedo are most apparent when the 

 subject is in circuit with the whole battery (which is vertical in 

 this case), i.e. when the lead-off is from upper and under surface 

 of the fish. In Gymnotus, too, and in Malapterurus, the shock is 

 more powerful in proportion as the contacts are further apart, and 

 the conductivity of the leading-off circuit more perfect, i.e. it is 

 strongest when the animal is held in the air by head and tail. 

 Some idea of the force of the electrical discharges from Gymnotus 

 is conveyed in the fact that Sachs obtained very marked shocks 

 on grasping an electrical eel 123 cm. long with rubber gloves. 

 On one occasion he received the full effect of the shock. He 

 relates that " he had fallen into the water, and emerged with wet 

 clothes clinging to him, while endeavouring (guarded with the 

 rubber gloves) to throw a lively, fresh-caught eel, over five feet 

 in length, into a trough. The animal escaped and fell on to both 

 his feet, so that its head made contact with one leg, its tail with 

 the other, remaining thus for several seconds. In this position, 

 when Dr. Sachs' legs completed the circuit between the poles of 

 the fish's battery, he received a rapid series of shocks which, 

 since they were not weakened by any deriving circuit, and were 

 easily conducted through the wet clothes, took effect with in- 

 describable intensity. Uttering loud cries of pain he stood as 

 though petrified by the shock, and was quite unable to rid himself 

 of the animal " (du Bois-Reymond, 4 c, p. 131). 



This was the effect of direct contact with the fish outside 

 the water, but the action is hardly less strong in the case of 

 immersion in the electrical current, where the lines of current which 

 traverse the water impinge upon the human body. In this mode 

 of action, to which, as Faraday points out, the electrical organs 

 are peculiarly adapted, each point in contact (or animal body) 

 receives a part of the discharge approximately proportionate to its 

 size. Even the early observations frequently refer to falling 

 under these conditions (du Bois-Reymond, 4 e, p. 132). Sachs 

 affirms that horses invariably drop when struck by gymnoti, so 

 that in traversing the canos it is necessary to seek out shallow 

 places, and the foremost rider pushes a stick into the water. 

 " The water becomes filled for a considerable distance with lines of 



