182 MARVELS OF THE ANIMAL WORLD 



which may cause him to tumble headlong into 

 the water. Although the electrical current trans- 

 mitted by the larger eels is suffi iently powerful 

 to kill those creatures which may happen to come 

 into contact thereto, yet its strength depends a 

 great deal upon the manner in which it is discharged, 

 the shock being much more severe when the head 

 and the tail of the fish are both brought into contact 

 with different portions of a victim's body than if 

 only one part be touched, and that by a single 

 point of contact. 



Professor Owen records some interesting experi- 

 ments made upon one of these fish by Professor 

 Faraday, and writes : — ' That the most powerful 

 shocks were received when one hand grasped the 

 head and the other the tail of the gymnotus I 

 had painful experience, especially at the wrists, 

 the elbow, and across the back. But our distin- 

 guished experimenter showed us that the nearer 

 the hands were together, within certain limits, 

 the less powerful was the shock. He demonstrated 

 by the galvanometer that the direction of the electric 

 current was always from the anterior part of the 

 animal to the posterior parts, and that the person 

 touching the fish with both hands received only 

 the discharge of the parts of the organs included 

 between the points of contact. Needles were 

 converted into magnets, iodine was obtained by 

 polar decomposition of iodide of potassium, and, 

 availing himself of this test. Professor Faraday 

 showed that any given part of the organ is negative 

 to other parts before it, and positive to such as 



