120 EXPERIMENTS ON THE GYMNOTUS. 



it be capable of directing the action of its organs to an 

 external object. We often tried, both insulated and other- 

 wise, to touch the fish, without feeling the least shock. 

 When M. Bonpland held it by the head, or by the middle of 

 the body, while I held it by the tail, and, standing on the 

 moist ground, did not take each other's hand, one of us 

 received shocks, which the other did not feel. It depends 

 upon the gymnotus to direct its action towards the point 

 where it finds itself most strongly irritated. The discharge 

 is then made at one point only, and not at the neighbouring 

 points. If two persons touch the belly of the fish with their 

 fingers, at an inch distance, aud press it simultaneously, 

 sometimes one, sometimes the other, will receive the shock. 

 In the same manner, when one insulated person holds the 

 tail of a vigorous gymnotus, and another pinches the gills or 

 pectoral fin, it is often the first only by whom the shock is 

 received. It did not appear to us that these differences 

 could be attributed to the dryness or moisture of our hands, 

 or to their unequal conducting power. The gymnotus 

 seemed to direct its strokes sometimes from the whole sur- 

 face of its body, sometimes from one point only. This 

 effect indicates less a partial discharge of the organ com- 

 posed of an innumerable quantity of layers, than the faculty 

 which the animal possesses, (perhaps by the instantaneous 

 secretion of a fluid spread through the cellular membrane,) 

 of establishing the communication between its organs and 

 the skin only, in a very limited space. 



Nothing proves more strongly the faculty, which the 

 gymnotus possesses, of darting and directing its stroke 

 at will, than the observations made at Philadelphia and 

 Stockholm,* on gymnoti rendered extremely tame. When 



* By MM. Williamson and Fahlberg. The following account is given 

 by the latter gentleman. " The gymnotus sent from Surinam to M. 

 Norderhng, at Stockholm, lived more than four months in a state of 

 perfect health. It was twenty-seven inches long ; and the shocks it gave 

 were so violent, especially in the open air, that I found scarcely any 

 means of protecting myself by non-conductors, in transporting the fish 

 from one place to another. Its stomach being very small, it ate little 

 at a time, but fed often. It approached living fish, first sending them 

 fronn afar a shock, the energy of which was proportionate to the size ot 

 the prey. The gymnotus seldom failed in its aim ; one single stroke 

 was almost alwaj 3 sufficient to overcome the resistance which the strata 



