Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 2 - By Alexander Von Humboldt And Aime Bonpland.
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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, and 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 surface
of its body, sometimes from one point only. This effect indicates less
a partial discharge of the organ composed 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. (* By MM. Williamson and Fahlberg. The following
account is given by the latter gentleman. "The gymnotus sent from
Surinam to M. Norderling, at Stockholm, lived more than four months in
a state of perfect health.
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