Читать книгу Life at the Zoo: Notes and Traditions of the Regent's Park Gardens онлайн

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The truth of Humboldt’s account of the taking of the electric eels is sometimes doubted. But apart from the credit due to the deliberate utterances of one of the greatest minds of modern days, the accuracy of whose views, even when he put them forward as mere probable surmise, is being constantly verified by later experience, the powers of the creatures, even of the small specimen brought to this country, are so astonishing as to make Humboldt’s account not err on the side of the marvellous.

It would be difficult, unless the opportunity existed of taking a plunge into a tank large enough to swim in, and well stocked with electric eels, to realize by personal experience the precise effect of the shocks upon the horses; but a record of the writer’s sensations when in personal contact with these uncanny creatures may perhaps give some notion of the strength of their electric power. The largest of the pair in Regent’s Park, about 4½ ft. in length, thick and deep, and probably weighing from 16 lbs. to 18 lbs., was moving sluggishly on the bottom of the tank, and was slowly raised to the surface by a landing-net. As its side became visible, its resemblance to a “cooling cast” was even closer than when seen from above. When grasped in the middle of the back, there was just time to realize that it had none of the “lubricity” of the common eel, when the first shock passed up the arm with a “flicker” identical with that which a zig-zag flash of lightning leaves upon the eye, and, as it seemed, with equal speed. A second and third felt like a blow on the “funny-bone,” and the hand and arm were involuntarily thrown back with a jerk which flung the water backwards on the pavement and over the keeper who was kindly assisting in the enterprise. This slight mishap recalled a far less agreeable result of a shock inflicted on a previous inquirer, whose recoiling hand had struck the assistant a severe blow in the face. Unwilling to be baffled by a fish less in size than the salmon which form the common stock of a fishmonger’s window, the writer once more endeavoured to hold the eel at any cost of personal suffering. But the electric powers were too subtle and pervading to be denied. The first muscular quiver of the fish was resisted; but at the second, the sense of vibration set up became intolerable, and the enforced release was as rapid and uncontrollable as the first. The smaller eel was neither so vigorous nor so resentful as its fellow. But though the first and second shocks did not compel the grasp to relax, a third was equally intolerable with that given by the larger fish. The electrical power seems to increase rapidly in the heavier eels. One of 5 ft. in length, which appeared to be nearly dead when it arrived at the Gardens, and was therefore handled without ceremony, inflicted a shock which, as the keeper stated, “nearly sent him on his back;” and the same fish, when being carried by hand in a tub up to the rooms of the Royal Society, sent a shock through the water which nearly caused the downfall of fish and bucket alike. This power of projecting its electric discharge, either through the water or by means of any conductor, to the object which it desires to paralyze, may be well observed at the Zoo. The usual way in which the shocks are received is by grasping a copper-rod, which is placed in contact with the fish’s back. But it is when in pursuit of the small fish which form its food that the “range” of the eel’s battery is best seen. On the last occasion on which the writer was present at the eel’s feeding-hour, eight or ten lively gudgeon were taken from a pail, and placed in the eel’s tank. The small fish at once dived to the bottom, as is their habit, and sought refuge in the corners, or at the angle made by the meeting of the base and sides of the stone cistern. Every one of the fish was killed by electric shock before being eaten; but in the case of those in the corners, it was impossible for the fish to bring the electric organ, which lies on each side of the lower part of the tail, into direct contact. The eel, therefore, swam past them, like a torpedo-boat which intends to discharge its broadside torpedoes, and as the battery came opposite, the fish gave a slight quiver, which instantaneously produced a violent shock in the gudgeon, and turned it belly upwards. After three had been killed and eaten, the shocks became weaker, and the other gudgeon seemed only partly paralyzed by the first shock, and sometimes recovered and swam away in a crippled condition until benumbed by a second shock. One fish which was “shocked” and left for dead while the eel went in pursuit of more, recovered after a few minutes, and was subsequently pursued, received a direct shock from the eel’s side, and was killed. The inference suggested by the writer’s own experience of the violence of the shocks inflicted, though with different degrees of intensity, is that the eel controls the power of the electrical discharge at will, just as it controls any other function which has its initiative in muscular action; and that the gudgeons received enough, and no more, than was sufficient to paralyze them, and make them easy victims for the slow-moving eel.