84 



ANIMAL ELECTRICITY. 



it is more so than the shock produced by the 

 Leyden phial ; and Contigliachi compares it 

 to that caused by the contact of two poles of 

 the voltaic pile. Ingenhousz thus describes 

 his sensations under the discharge of the tor- 

 pedo. " I took a torpedo in my hand, so that 

 my thumbs pressed gently on the upper surface 

 of the lateral fin, whilst my forefingers pressed 

 the opposite side. About one or two minutes 

 after I felt a sudden trembling in my thumbs, 

 which extended no further than my hands ; 

 this lasted about two or three seconds. After 

 some seconds more, the same trembling was 

 felt again. Sometimes it did not return in 

 several minutes, and then came again at veiy 

 different intervals. Sometimes I felt the trem- 

 bling both in my fingers and my thumb. These 

 tremors gave me the same sensations as if a 

 great number of very small electrical bottles 

 were discharged through my hand very quickly 

 one after the other. Sometimes the shock was 

 very weak, at other times so strong that I was 

 very near being obliged to quit my hold of the 

 animal."* Walsh ascertained that the same 

 torpedo has the power of discharging in two 

 different manners, so as to produce at one 

 time the effect described by Ingenhousz as a 

 trembling, and at another time a sharp instan- 

 taneous shock closely resembling that produced 

 by the discharge of a Leyden phial.f Accord- 

 ing to Sir II. Davy, " whoever has felt the 

 shocks both of the voltaic battery and of the 

 torpedo must have been convinced, as far as 

 sensation is concerned, of their strict ana- 



iogy-"t 



Sometimes the torpedo buries itself in the 

 sand left dry at ebb-tide; and it has occasionally 

 happened, according to some naturalists, that 

 persons walking across the sand, and treading 

 upon the spot beneath which the electrical fish 

 lay concealed, have received his discharge so 

 fully as to be thrown down. 



The effects produced by the discharge of the 

 Gymnotus are more severe. When it is touched 

 with one hand, a smart shock is generally felt 

 in the hand and fore-arm ; and, when both 

 hands are applied, the shock passes through the 

 breast The discharges of large fish (they grow 

 to the length of twenty feet in their native 

 rivers) sometimes prove sufficient to deprive 



Phil. Trans. 1775, 2. 



t Phil. Trans. 1773, 467. 



t Phil. Trans. 1829, 15. 



The experience of Dr. Davy would lead us to 

 call in question the possibility of such an occurrence ; 

 for he has always found it necessary to touch the 

 opposite surfaces of the electrical organs or organ to 

 receive the torpedo's shock. He has irritated torpe- 

 dos very frequently by pressing with the finger on 

 different parts of the back, but however much the 

 fish were irritated he never had any sensation re- 

 ferrible to the passage of the electricity. In corro- 

 boration of his opinion that the fish cannot give a 

 shock excepting the two opposite surfaces of its 

 electrical organs be connected by conductors, Dr.D. 

 states that when one surface only is touched and irri- 

 tated, the fish themselves appear to make an effort 

 l<> bring, by muscular contraction, the border of the 

 other surface into contact with the offending body. 

 This is done even by fatal fish. Phil. Trans. 

 1834. 



men, while bathing, of sense and motion. 

 1'ermin found that a strong one had power to 

 give a shock to fourteen persons at the same 

 time ; and other experimenters have seen twenty- 

 seven persons simultaneously receive its shock. 

 Ilumboldt states that, having placed his feet 

 on a fresh Gymnotus, he experienced a more 

 dreadful shock than he ever received from a 

 Leyden phial, and that it left a severe pain in 

 his knees and in other parts of his body, which 

 continued for several hours. Sometimes the 

 discharge occasions strong contractions of the 

 flexor muscles of the hand which grasps the 

 fish, so that it cannot be immediately let go ; 

 and then, the shock being repeated still more 

 severely, painful sensations are experienced 

 thoughout the whole body, and headache with 

 soreness of the legs remains for some time after.* 

 Paralytic affections, as well as giddiness and 

 dimness of sight, are said sometimes to have 

 followed the reception of strong discharges. f 

 It is stated by some observers that there are men 

 who are as insusceptible of the shocks of electrical 

 fishes as others are of those from the Leyden 

 phial ; and that women affected with nervous 

 diseases are seldom conscious of receiving the 

 discharge. Kaempfer assertedj that, by sup- 

 pressing respiration for a short time, any man 

 may render himself insensible to the torpedo's 

 discharge; but this has been disproved by 

 Walsh and other observers. 



Regarding the effects of the discharges of the 

 other electrical fishes, we know very little. The 

 shock given by the Malapterurusof the Nile and 

 Niger (Silurus, Linn.) is said to be more feeble 

 than that of the Torpedo, and yet very painful, 

 attended with trembling, and followed by 

 soreness of the limbs. In attempting to take an 

 individual of Tetraodon electricus in his hand, 

 Lieutenant Paterson (its discoverer) received so 

 severe an electrical shock that he was obliged to 

 quit his hold. 



The effects of the discharge of the Gymnotus 

 on the larer animals cannot be better illustrated 

 then by the account which Ilumboldt has given 

 of the method of capturing the fish adopted by 

 the South American Indians. This method 

 consists in irritating the fish by driving horses 

 into the pools which it inhabits. It directs 

 its electricity in repeated discharges against 

 these horses until it becomes exhausted, when it 

 falls an easy and harmless prey into the hands of 

 the fishermen. Humboldt saw about thirty 

 wild horses and mules forced into a pool con- 

 taining numerous Gymnoti. The Indians sur- 

 rounded the banks closely, and being armed 

 with harpoons and long reeds, effectually pre- 

 vented the escape of the horses. The fishes 

 were aroused by their trampling, and, coming 

 to the surface, directed their electrical discharges 

 against the bellies of the intruders. Several 

 horses were quickly stunned, and disappeared 

 beneath the surface of the water. Others, ex- 

 hibiting signs of dreadful agony, hurried to the 

 bank, with bristled mane and haggard eye, but 



* Bryant, Trans. Amer. Soc. ii. 167. 

 t Flagg, do. ii. 170. 

 { Amcen. Exot. 514, 



