we gradually expose the animal to a more violent cold, and it becomes frozen, death ensues.

When

Warmth is the most natural cause of the animal's awaking there are other causes, however, and cold is one of them. the animal awakes from any given cause, respiration and circulation recommence with the usual degree of heat. The profoundness of the sleep is different, according to the species. Some animals awake several times in winter: the bear and the badger are subject to a slight sleep only: the dormouse allows itself to be dissected without exhibiting any signs of pain.

They evacuate their bowels be fore going to sleep; but they eat during the short times in which they are awake: they transpire but very little. The above are such facts as have been clearly as. certained.

With respect to the predisposing causes, i. e. why some animals are subject to sleep in winter, and others not; and with respect to the preserving causes, i. e. what renders them susceptible of reviv. ing, notwithstanding the suspension of functions which seem most necessary to life,-nothing yet has been advanced which offers a satisfactory solution of these questions.

On the Generation, and other obscure Facts in the Natural History of the common Eel. By Mr. J. Carr, of Manchester. [From the Philosophical Magazine for October, 1809.]

IN all inland waters eels abound

without number in summer, bai disappear in winter. This disappearance has been variously ac counted for, and it has been very generally imagined that a large proportion hibernate by bedding themselves in mud; a notion, which, I believe, is quite as vi. sionary as the hibernation of swal. lows under water. Were eels ever in the habit of penetrating into mud, they would naturally enough shelter themselves therein when ex. posed to imminent danger, and no other mode of escape presented it. self; but I have seen very many instances of muddy pools, par. posely and speedily drained of, where multitudes of eels crawled over the light surface of the mud in all directions to escape, and without ever attempting to conceal themselves by penetrating into it. The full and clear eye of the ed also furnishes evidence that Nature never intended the animal to be buried under mnd.

The disappearance of eels in rivers and brooks may be well ac counted for by their emigration to the sea. This emigration is called their running. It commences in autumn, when immense quantities pass down the streams. Great numbers take the advantage of de. scending with floods, but a large proportion pass downwards in the night, and only in the darkest and most tempestuous nights. Moonshine wholly suspends their pro. gress; and even a temporary gleam of light, when the night is otherwise favourable, immediately interrupts their journey. This proves that their emigration is not a casual but a premeditated system in their existence: and it also displays their instinctive

stinctive cunning; for, being an easy prey, when discovered, to otters, herons, and other nocturnal enemies, it is only in the darkest nights that they can travel in safe. ty. During the period of their run, vast quantities are caught in bag.nets set across the streams. There is reason to suspect that all the ells in rivers do not run for the sea, as very early in the spring large cels abound in rivers at such a distance in-land,, as renders it highly improbable that they can have ascended so far at so early a period; and, indeed, it is yet an unascertained fact, whether, of the vast multitude which unquestionably do pass downwards to the sea, any of them do again return and ascend to any distance up the streams. If, indeed, this retrograde emigration really existed to any extent, there are thousands of situations on our streams where it must have been every season perceived; and yet it has not only not been discovered, but the instances are frequent, where the obstacles on many of our streams render it impracticable, and where, nevertheless, large eels are found above these obstacles as early and as abundantly as below them. The probability, therefore is, that few or none of the vast numbers which descend the streams ever again return; and then, as they are never discovered in the sea itself, the question of what ultimately becomes of them, is just as obscure as that of their generation.

There are many lakes, and mul titudes of pools, abounding with eels, and from which they cannot run on account of the insufficiency of the outlets; and in these situa. tions the eels most certainly conti

nue during the period of their ex. istence. There, however, they regularly disappear in winter, and the manner of their hibernating is entirely unknown; but as no species of animal with which we are acquainted ever does breed during the time of its hibernation, (the thing, indeed, seeming physically impossible,) and as cels in these confined situations are taken at all other times, without any vestige of propagation being discovered amongst them, the inference seems. conclusive, that eels never do, under any circumstance, breed in fresh water. Were it, indeed, practicable in a single instance, it would be equally so in thousands of others where the circumstances are so similar; and it would be pass ing strange if a solitary quarry-pit, which had been excluded for a do. zen years even from day-light, were to discover to us an occurrence which is never displayed in our multitudinous open pools, where the same animals are equally restricted from escape.

In contradistinction to the vast emigration of old eels down the streams in autumn, an immensely greater migration of young ones commences up the streams in spring and summer. Their size varies between the smallest and the largest darning needle. They are called elvers, and abound in some of our large rivers to an inconceivable extent. In some places bushels of them are taken with baskets fixed on to the ends of poles, and drawn swiftly through the water. Their progress is always along the banks, and numerous portions pass up into all the lateral streams. The smallest brook and the minutest rill that can run receive

their proportion; and it is solely in this way that every piece of water, however, or wherever it may be situated, receives the cels that are found in it. The smallest possible trickling of water from any pool to the nearest brook, is suffi cient to enable these little indefati. gable animals to wind their way up to the source. The instinct, in deed, which impels them upwards against all moving waters seems incessant and irresistible; it sur. mounts every difficulty, and perseveres successfully against every obstacle, however imperious. During the low state of streams in the early part of summer, they may be found at wiers, mill-dams, cascades, and other elevations across the streams, ascending by the mar. gin of the water perpendicular walls many feet in height, where the least crevice in the stone, or patch of moss, affords them a hold; and they will even find their way over vertical dry boards, by adroit. ly employing their glutinous exterior. I have taken them in hand. fuls, from patches of wet moss against erect walls, completely out of the water, and where the height and distance to be surmounted would require the persevering ef. forts of many days. In very small pellucid brooks, adjacent to rivers where they abound, they may be seen wriggling up the little streams in endless succession for weeks to gether. Great numbers doubtless perish by ascending the temporary rilis produced from rain, and by reaching spring-heads, and situations where the water is insufficient for their growth and sup. port; but in this, as in every other instance, provident Nature has guarded against all such casual ex

penditure, by the superabundance of the production.

In the large rivers communi. cating with the sea, although the elvers appear to advance in wast bodies, I do not imagine their mi. gration, either in its commence. ment or progress, is made in concerted shoals; it seeming more probable that the number found together is accidental, and arises from the continual supply sent off from the quarter where they ori. giuate. This is confirmed in the small streams, where each indivi dual is soen making its way by its own solitary efforts.

In summer all the large eels in rivers and brooks conceal them. selves during the day under large stones and roots of trees, and in the crevices of rocks and walls, and even in earth-holes of the banks; and in these situations they obtain a large proportion of their food, being always on the watch to seize small fish, or other prey that the stream or accident throws into their concealment; and I think it is much more pro. bable that the eels which do not find their way down to the sea, pass the winter in similar situa tions, rather than bedded in mud, or in any other of the fanciful modes which have been assigned them.

Such are a few of the principal facts in the natural history of the common eel, a creature which every where surrounds us in the greatest abundance, and yet its origin and final disposal are equally unknown. That it never does breed in fresh water seems to be a fact well established; and the periodical descent of the old ones to the sea, and ascent of the young

ones