GYMNOTLS ELECTUrcUS. 171 



make experiments. Tlie results of Humboldt's obscrva- chap. xv. 



tions on these animals may be stated briefly as follows : — ,, "^ , 

 mi -11 1 ■ -1 . Expennients 



liie gymnotus is the largest electrical fish known, on the 



some of those measured by him being from 5 feet 4 ^'i™^*"'"^ 



inches to 6 feet 7 inches in length. One, 4 feet 1 inch 



long, weighed 16| Troy pounds, and its transverse 



diameter was 3 inches 7^ lines. The colour Avas a 



fine olive-green ; tlie under part of the head yellow 



mingled with red. Along the back are two rows of 



small yellow spots, each of which contains an excretory 



aperture for the mucus, with which the skin is constantly 



covered. The swimming-bladder is of large size, and 



before it is situated another of smaller dimensions ; the 



former separated from the skin by a mass of fat, and 



resting upon the electric organs, which occupy more 



than two-thirds of the fish. 



It would be rash to expose one's self to the first Danger from 

 shocks of a very large individual, — the pain and numb- *^^ shock, 

 ness which follow in such a case being extremely 

 violent. When in a state of great weakness, the animal 

 produces in the person who touches it a twitching, 

 which is propagated from the hand to the elbow ; a 

 kind of internal vibration lasting two or three seconds, 

 and followed by painful torpidity, being felt after every 

 stroke. The electric energy depends upon the will of 

 the creature, and it directs it toward the point where it 

 feels most strongly irritated. The organ acts only Organ of 

 under the hnmediate influence of the brain and heart ; ^'^^''^"^ 

 for, when one of them was cut through the middle, the 

 fore part of the body alone gave shocks. Its action on 

 man is transmitted and intercepted by the same sub- 

 stances that transmit and intercept the electrical current 

 of a conductor charged by a Leyden jar or a Voltaic 

 pile. In the water the shock can be conveyed to a con- 

 siderable distance. No spark has ever been observed to 

 issue from the body of the eel when excited. 



The gymnoti are objects of dread to the natives, and 

 their presence is considered as the principal cause of the 



