In 1838 there was brought to London, and exhibited at the Adelaide
Gallery, in the Strand, a living specimen of the electric eel, or
gymnotus, being the first received in this country alive within the
present century. It was fed upon fish, and occasionally with bullock's
blood, and was kept warm by water, artificially heated. With this eel
several interesting experiments were made, allowing periods of rest from
a week to a month between each set. One of these is thus described:--
"I was so fortunate (says Professor Owen) as to witness the experiments
performed by Professor Faraday on the large gymnotus which was so long
preserved at the Adelaide Gallery, in London. That the most powerful
shocks were received when the one hand grasped the head, and the other
hand the tail of the gymnotus, I had painful experience, especially at
the wrists, the elbow, and across the back. But our distinguished
experimenter showed us that the nearer the hands were together, within
certain limits, the less powerful was the shock. He demonstrated by the
galvanometer that the direction of the electric current was always from
the anterior parts of the animal to the posterior parts, and that the
person touching the fish with both hands received only the discharge of
the parts of the organs included between the points of contact. Needles
were converted into magnets; iodine was obtained by polar decomposition
of iodide of potassium; and availing himself of this test, Professor
Faraday showed that any given part of the organ is negative to other
parts before it, and positive to such as are behind it. Finally, heat
was evolved, and the electric spark obtained."
------------------