These fish, which grow to the length of a foot, travel in large droves with this view; they move by night, and their motion is said to be like that of the two-footed lizard.* A strong serrated arm constitutes the first ray of its pectoral fin. Using this as a kind of foot, it should seem, they push themselves forward, by means of their elastic tail, moving nearly as fast as a man will leisurely walk. The strong plates which envelope their body, probably facilitate their progress, in the same manner as those under the body of serpents, which, in some degree, perform the office of feet. It is affirmed by the Indians, that they are furnished with an internal supply of water, sufficient for their journey.”+ Mr Kirby mentions some other tribes of migrating fishes; and, among these, one found in Tranquebar, by Daldorff, which not only creeps upon the shore, but even climbs the fan-palm, in pursuit of certain crustaceans which form its food. Its structure is admirably adapted to this extraordinary instinct. The lobes of its gillcovers are so divided and armed, as to be employed together or separately, as hands, for the suspension of the animal, till, by unsheathing its dorsal and anal fins, which at other times it folds up into the cavity of its body, and, fixing them in the bark, it prepares to take another step. How curious are these contrivances, and how varied the resources of the Author of Nature! The instances now mentioned, however, are, in reality, no more worthy of attention than the instincts of those animals with which we are most familiar. We are only more surprised and impressed with them, on account of their singularity. The hand of a wonder-working God is every where. * Bipes. † Kirby's Bridgewater Treatise, vol. i. pp. 116-122. EIGHTH WEEK-THURSDAY. MIGRATION OF EELS. THE following observations of Sir Humphrey Davy, in his "Salmonia," on the migration of eels, are too curious to be omitted: "There are two migrations of eels, one from, and the other to, the sea: the first in spring and summer; the second in autumn, or early in winter. The first, of very small eels, which are sometimes not more than two, or two and a-half inches long; the second, of large eels, which sometimes are three or four feet long, and weigh from ten to fifteen, or even twenty pounds. There is great reason to believe, that all eels found in fresh water are the results of the first migration. They appear in millions in April and May, and sometimes continue to rise as late even as July and the beginning of August. I remember this was the case in Ireland in 1823. It had been a cold backward summer; and when I was at Ballyshannon, about the end of July, the mouth of the river, which had been in flood all this month, under the fall, was blackened by millions of little eels, about as long as the finger, which were constantly urging their way up the moist rocks by the side of the fall. Thousands died; but their bodies remaining moist, served as a ladder for others to make their way; and I saw them ascending even perpendicular stones, making their road through wet moss, or adhering to some eels that had died in the attempt. Such is the energy of these little animals, that they continue to find their way in immense numbers to Loch Erne. The same thing happened at the Fall of Bann, and Loch Neah is thus peopled with them. Even the mighty Fall of Schaffhausen does not prevent them from making their way to the Lake of Constance, where I have seen many very large eels. "There are eels in the Lake of Neufchatel, which communicates by a stream with the Rhine; but there are none on the Leman Lake, because the Rhone makes a subterraneous fall below Geneva; and though small eels can pass by moss, or mount rocks, they cannot penetrate limestone, or move against a rapid descending current of water, passing, as it were, through a pipe. Again, no eels mount the Danube from the Black Sea; and there are none found in the great extent of lakes, swamps, and rivers, communicating with the Danube, though some of these lakes and morasses are wonderfully fitted for them; and though they are found abundantly in the same countries, in lakes and rivers connected with the ocean and the Mediterranean; yet, when brought into confined water in the Danube, they fatten and thrive there. "As to the instinct which leads young eels to seek fresh water, it is difficult to reason; probably they prefer warmth, and, swimming at the surface in the early summer, find the lighter water warmer, and likewise containing more insects, and so pursue the courses of fresh water, as the waters from the land, at this season, become warmer than those of the sea.*. Mr Couch says, (Lin. Trans., part 14, p. 70), that the little eels, according to his observation, are produced within reach of the tide, and climb round falls to reach fresh water from the sea. I have sometimes seen them, in spring, swimming in immense shoals in the Atlantic, in Mount Bay, making their way to the mouths of small brooks and rivers. When the cold water from the autumnal floods begins to swell the rivers, this fish tries to return to the sea; but numbers of the smaller ones hide themselves during the winter in the mud, and many of them form, as it were, masses together. "Various authors have recorded the migration of eels *The justice of this suggestion seems very doubtful.-H. D. in a singular way, such as Dr Plot, who, in his History of Staffordshire, says that they pass in the night, across meadows, from one pond to another;* and Mr Anderson, (Trans. Royal Soc.), gives a distinct account of small eels rising up the flood-gates and posts of the water-works of the city of Norwich; and they made their way to the water above, though the boards were smooth planed, and five or six feet perpendicular. He says, when they first rose out of the water upon the dry board, they rested a little, which seemed to be till their slime was thrown out, and sufficiently glutinous, and then they rose up the perpendicular ascent as if they had been moving on a plain surface. There can, I think, be no doubt, that they are assisted by their small scales, which, placed like those of serpents, must facilitate their progressive motion. These motions have been microscopically observed by Leuwenhoek (Phil. Trans. vol. iv.). “Eels migrate from the salt water, of different sizes; but I believe never, when they are above a foot long, and the great mass of them are only from two and a half to four inches. They feed, grow, and fatten, in fresh water. In small rivers they are seldom very large; but in large deep lakes they become as thick as a man's arm, or even leg; and all those of a considerable size attempt to return to the sea in October or November. Those that are not of the largest size, pass the winter in the deepest parts of the mud of rivers and lakes, and do not seem to eat much, and remain, I believe, almost torpid. Their increase is certainly not known in any given time, but must depend on the quantity of their food; but it is probable that they do not become of the largest size, from the smallest, in one or even two seasons. As very large eels, after having migrated, never return to the river * There can be no doubt that eels occasionally leave the water for the land. Mr Jesse, who is an accurate inquirer, says, "Eels certainly come upon grass lands, to feed at night upon worms and snails. In the meadows at Barford, in Warwickshire, they have been cut in two by the mowers, and an old keeper there assured a friend of mine, that he had frequently intercepted them, on their way back to the river, early in the morning. Their movements on land were very quick.—Jesse's Gleanings, 3d series, p. 68. again, they must, (for it cannot be supposed that they all die immediately in the sea), remain in salt water; and there is great probability that they are then confounded with the conger, which is found of different colours and sizes, from the smallest to the largest, from a few ounces to one hundred pounds weight." I shall conclude this paper by some observations of Mr Jesse, on the hybernation of eels. "That eels hybernate during the cold months there can, I think, be little doubt, few or none being caught at that time. I have endeavoured also, but without success, to procure eels in the winter, from those places in the River Thames where, I have every reason to believe, they go to spawn. I read what an account which, if correct, would serve to prove I have now stated. A boy at Arthurstown, in the county of Wexford, perceived something of a very unusual appearance floundering upon the sand at low water. Upon a nearer approach he found it to be a quart bottle, which showed many symptoms of animation. He seized it, and brought it in. It was found to contain an eel so much thicker than the neck of the bottle, that it must be supposed the eel made its lodgement there, when it was younger, and of course smaller. It was necessary to break the bottle for the purpose of liberating the fish. "If this account be true, it goes to prove, in a curious way, as far as one instance can do so, the propensity which eels have to hybernate during the cold months. It also seems to prove, that they do this in the tide-way if they can, and that they neither feed nor deposit their spawn till the season of hybernation is over. It is indeed a general opinion among old fishermen that eels cannot bear cold."* * Jesse's Gleanings, 3d series, pp. 69-70. |