Eel, a family of serpent-shaped fish. They are long and slender with soft, slimy skins. The body is round or else ribbon-shaped. The scales are imbedded so deep that they cannot be seen or felt till the skin is dried. The gill openings are small, and close so tightly that eels can live out of water for some time. Some species even leave the water and glide over meadows at night in search of food. They are found in warm and temperate climates. Some species inhabit salt, others fresh water, and others again migrate. Fresh water eels lie dormant in muddy bottoms during the winter. Aristotle thought they sprang from mud. A popular idea in England at one time was that the hair of a stallion's tail, left in water, would turn into eels. It is now known that they breed by means of eggs or ova like other fishes. A nest of pebbles in running water is preferred. A colony of eels in the Saco River, Maine, formed a heap of stones fifteen feet long and three feet high, in which to deposit eggs. The eel grasps a stone, sucker fashion, and drags it along the bottom till it is in place. The conger eel of European waters attains a length of three to ten feet and a weight of five to one hundred pounds. It preys on other fish. The sharp-nosed eel of Europe swarms in the rivers of Great Britain, and is a staple article in the fish markets. The greenish olive eel of this country is abundant in streams from Maine to the Mississippi and Brazil. It is taken with spears by torchlight, and in eel-pots. The latter is a willow-basket contrivance to which Washington Irving refers in describing the schoolhouse of Sleepy Hollow, so constructed that eels can enter but not get out again. An electric eel called the gymnotus, found in the swamps of South America appears to be charged with electricity capable of giving a man a severe shock. It being very difficult to catch the gymnoti with nets, on account of their extreme agility, it was resolved to procure some by intoxicating or benumbing them with the roots of certain plants, which when thrown into the water produce that effect. At this juncture the Indians informed them that they would fish with horses, and soon brought from the savanna about thirty of these animals, which they drove into the pool. The extraordinary noise caused by the horses' hoofs makes the fishes issue from the mud and excites them to combat. These yellowish and livid eels, resembling large aquatic snakes, swim at the surface of the water, and crowd under the bellies of the horses and mules. The struggle between animals of so different an organization affords a very interesting sight. The Indians, furnished with harpoons and long slender reeds, closely surround the pool. Some of them climb the trees, whose branches stretch horizontally over the water. By their wild cries and their long reeds they prevent the horses from coming to the edge of the basin. The eels, stunned by the noise, defend themselves by repeated discharges of their electrical batteries, and for a long time seem likely to obtain the victory. Several horses sink under the violence of the invisible blows which they receive in the organs most essential to life, and, benumbed by the force and frequency of the shocks, disappear beneath the surface. Others, panting, with erect mane, and haggard eyes expressive of anguish, raise themselves and endeavour to escape from the storm which overtakes them, but are driven back by the Indians. A few, however, succeed in eluding the active vigilance of the fishers; they gain the shore, stumble at every step, and stretch themselves out on the sand, exhausted with fatigue, and having their limbs benumbed by the electric shocks of the gymnoti. In less than five minutes two horses were killed. The eel, which is five feet long, presses itself against the belly of the horse, and makes a discharge along the whole extent of its electric organ. It attacks at once the heart, the viscera, and the caeliac plexus of the abdominal nerves. It is natural that the effect which a horse experiences should be more powerful than that produced by the same fish on man, when he touches it only by one of the extremities. The horses are probably not killed, but only stunned; they are drowned from the impossibility of rising amid the prolonged struggle between the other horses and eels.--Alexander von Humboldt.