t^catclimg them by means of Wild Horses. 245 
covered with a mucous matter, which, as Volta has proved, con- 
ducts electricity twenty or thirty times better than pure water. 
It is in general somewhat remarkable^ that no electrical fish, yet 
discovered ^ in the different parts of the world, is covered with 
scales. 
It would be temerity to expose ourselves to the first shocks 
of a very large and strongly irritated gymnotus. If by chance 
you receive a stroke before the fish is wounded, or wearied by a 
long pursuit, the pain and numbness are so violent, that it is im- 
possible to describe the nature of the feeling they excite. I do not 
remember having ever received from the discharge of a large Ley- 
den jar, a more dreadful shock than that whicli I experienced by 
imprudently placing both my feet on a gymnotus just taken out 
of the water. I was affected the rest of the day with a violent 
pain in the knees, and in almost every joint. To be aware of 
the difference, which is sufficiently striking, that exists between 
file sensation produced by the pile of Volta and anelectrical fish, 
the latter should be touched when they are in a state of extreme 
weakness. The gymnoti and the torpedoes then cause a twit- 
ching, w hich is propagated from the part that rests on the 
electric organs as far as the elbow. We seem to feel at every 
stroke an internal vibration, that lasts two or three seconds, and 
is followed by a painful numbness. 
Gymnoti are neither charged conductors, nor batteries, nor 
electromotive apparatuses, the shock of which is received every 
time they are touched with one hand, or when both hands are 
applied to form a conducting circle between two heterogeneous 
poles. The electric action of the fish depends entirely on its 
will ; whether because it does not keep its electric organs al- 
ways charged, or by the secretion of some fluid, or by any 
other means alike mysterious to us, it be capable of directing the 
action of its organs to an external object. We often both tried, 
both insulated and uninsulated, to touch the fish, without feel- 
ing the least shock. When Mr Bonpland held it by the head, 
or by the middle of the body, wffiile I held it by the tail, and, 
standing on the moist ground, did not take each other's hand, 
* We yet know with certainty only seven electrical fishes ; Torpedo narke, Ris- 
so, t. unimaculata, t. marmorata, t. galvanii, Silurus electricus, Tetraodon electricus, 
Gymnotus electricus. 
