604 STING-RAYS. 



to retire to the larger pools or rivers. In the shallow ponds 

 of the forest they are easily driven out with long poles. 



Bates amused his native companions, who had thus caught 

 some of the creatures, by showing them how the electric 

 shock could pass from one person to another. They joined 

 hands in a line, while he touched the biggest and freshest of 

 the animals on the head with the point of his hunting-knife. 

 He found, however, that the experiment did not succeed more 

 than three times with the same eel when out of the water, 

 for the fourth time the shock was scarcely perceptible. 



The limbs even of the strongest. man are benumbed, and he is 

 struck down helpless, by a discharge from the battery of the 

 gymnotus. The organs which produce this curious electrical 

 effect are placed along the under side of the tail. They may 

 be compared to a series of columns inclosed in a thin mem- 

 brane packed closely together, which, consisting of a series of Hat 

 discs, may be imitated by placing a number of coins with 

 their discs parallel to each other, and with a bladder between 

 each, separated by a gelatinous substance. These columns 

 are technically called septa ; and Lacepede calculates that 

 two hundred and forty transverse membranes are packed in 

 each inch, thereby giving to an electric eel eight feet in length 

 an organ cavity of two hundred and forty-six square feet — 

 an enormous extent, as may be supposed, of electricity pro- 

 ducing surface. The whole apparatus is supplied with nerves 

 which run through the entire length of the body. 



STING-1LVVS. 



A fresh-water species of sting-ray is an inhabitant of the 

 creeks and lagoons of stagnant water ; and so infested are 

 some of them with the creatures, that it is almost certain 



