xi ELECTRICAL FISHES 42* 



was bisected, the anterior half alone twitched, and the experiments 

 of Sachs confirm this. He also, in individual cases, obtained 

 " powerful reflex discharges " from the headless trunk, which can 

 be sensibly felt, as well as expressing themselves by marked 

 deflections on the galvanometer. He explains the absence of 

 effect in the majority of cases as follows : " Smaller and smaller 

 sections of the organ are thrown into simultaneous activity by 

 the reflex, just as, on decapitating the common eel, localised 

 excitation of the skin is followed by more local contractions of 

 the muscles." A more exact investigation of these partial dis- 

 charges, by means of a superposed frog's leg, is very desirable. 



The effect of strychnine poisoning, on the other hand (the 

 action of which was proved by Matteucci and Boll on the torpedo), 

 is highly characteristic, and corresponds with what might be 

 expected. Marey, too, employed strychnine to produce reflex dis- 

 charges easily and certainly upon Torpedo, and he made graphic 

 records of the time-distribution of electrical strychnine-tetanus. 

 In order to poison the animal, he dissolved the poison in the 

 sea- water of its trough. Sachs observed convulsive spasms in 

 Gymnotus after the injection of strychnine, accompanied by re- 

 peated single discharges. Reflex excitability was much exag- 

 gerated. " The slightest tap on the wall of the thick wooden 

 trough produced reflex twitches and discharge." 



III. DISCHARGE FROM ARTIFICIAL EXCITATION OF THE 

 ELECTRICAL NERVES AND CENTRAL ORGANS 



Anatomical considerations at once make it clear that 

 Gymnotus, Raja, and Mormyrus are, among the electrical fishes, 

 the least suitable for indirect excitation of the organ, since the 

 anatomical arrangement of the very short electrical nerves 

 presents great difficulties to the dissection of a nerve-organ pre- 

 paration. " In Malapterurus, a cut which hardly draws a drop 

 of blood will expose a long tract of both the nerves, as if pre- 

 pared by nature. Regular strips may be cut out of the organ 

 with scissors, of any length and breadth, and these, bounded ex- 

 ternally by skin, internally by fascia, preserve their form well." 

 In Torpedo also, though with more difficulty, it is possible to 

 prepare and excite the four nerves that run from brain to organ. 

 In Gymnotus, on the other hand, about 250 nerves enter the elec- 



