‘This sight,’ says Humboldt, ‘involuntarily reminds the observer of the great pliability with which nature has endowed several plants and animals. Along with the fruits of Ceres, the horse and the ox have followed man over the whole earth, from the Granges to the La Plata, and from the coast of Africa to the mountain-plain of Antisana, which is more elevated than the lofty peak of Teneriffe. Here the northern birch-tree, there the date-palm, protects the tired ox from the heat of the mid-day sun. The same species of animal which contends in eastern Europe with bears and wolves, is attacked in another zone by the tiger and the crocodile.’
[Illustration: ELECTRICAL EEL. (GYMNOTUS ELECTRICUS.)]
But it is not the jaguar and the alligator alone which lie in wait for the South American horse, for even among the fishes he has a dangerous enemy. The rivers and marshes of the Llanos are often filled with electrical eels, which send forth at will from the under part of the tail a stunning shock. These eels are from five to six feet long. They are able, when in full vigour, to kill the largest animals, when they suddenly unload their electrical organs in a favourable direction. Humboldt having accidentally set his foot on a gymnote which had just been taken out of the water felt the whole day severe pains in the knees and almost in every joint. Lizards, turtles, and frogs seek the morasses where they are safe from their discharges, and all other fishes, aware of their power, fly at the sight of the formidable gymnotes. They stun even the angler on the high river-bank, the moist line serving as a conductor for the electric fluid. The capture of these eels affords a highly entertaining and animated scene. Mules and horses are driven into the pond which the Indians surround, until the unwonted noise and splashing of the waters rouse the fishes to an attack. Gliding along, they creep under the belly of the horses, many of whom die from the shock of their strokes; while others, with mane erect, and dilated nostrils, endeavour to flee from the electric storm which they have roused. But the Indians, armed with long poles, drive them back again into the pool.
Gradually the unequal contest subsides. Like spent thunderclouds, the exhausted fishes disperse, for they require a long rest and plentiful food to repair the loss of their galvanic powers. Their shocks grow weaker and weaker. Terrified by the noise of the horses, they timidly approach the banks, when, wounded with harpoons, they are dragged on shore with dry and nonconducting pieces of wood; and thus the strange combat ends.