a lake of Campania in Italy, near Baiae, famous among the ancients for its poisonous qualities. It is described by Strabo as lying within the Lucrine bay, deep and darksome, surrounded with steep banks that hang threatening over it, and only accessible by the narrow passage through which you fall in. Black aged groves stretched their boughs over the watery abyss, and with inpenetrable foliage excluded almost every ray of wholesome light; mephitic vapours ascending from the hot bowels of the earth, being denied free passage to the upper atmosphere, floated along the surface in poisonous mists. These circumstances produced horrors fit for such gloomy deities; a colony of Cimmerians, as well fitted to the rites as the places itself, cut dwellings in the bosom of the surrounding hills, and officiated as priests of Tartarus. Superstition always delighting in dark ideas, early and eagerly seized upon this spot, and hither she led her trembling votaries to celebrate her dismal orgies; here she evoked the manes of departed heroes—here she offered sacrifices to the gods of hell, and attempted to dive into the secrets of futurity. Poets enlarged upon the popular theme, and painted its awful scenery with the strongest colours of their art. Homer brings Ulysses to Avernus, as to the mouth of the infernal abodes; and in imitation of the Grecian bard, Virgil conducts his hero to the same ground. Whoever failed thither, first did sacrifice; and endeavoured to propitiate the infernal powers, with the assistance of some priests who attended upon the place, and directed the mystic performance. Within, a fountain of pure water broke out just over the sea, which was fancied to be a vein of the river Styx; near this fountain was the oracle; and the hot waters frequent in those parts were supposed to be branches of the burning Phlegthon. The poisonous effluvia from this lake were said to be so strong, that they proved fatal to birds endeavouring to fly over it. Virgil ascribes the exhalation not to the lake itself, but to the cavern near it, which was called Avernus, or Cave of the Sibyl, and through which the poets feigned a descent to hell. Hence the proper name of the lake is Lacus Avernus, the "lake near the cavern," as it is called by some ancient authors.

The holiness of these shades remained unimpeached for many ages: Hannibal marched his army to offer incense at this altar; but it may be suspected he was led to this act of devotion rather by the hopes of surprising the garrison of Puteoli, than by his piety. After a long reign of undisturbed gloom and celebrity, a sudden glare of light was let in upon Avernus; the horrors were dispelled, and with them vanished the sanctity of the lake: the axe of Agrippa brought its forest to the ground, disturbed its sleepy waters with ships, and gave room for all its malignant effluvia to escape. The virulence of these exhalations, as described by ancient authors, has appeared so very extraordinary, that modern writers, who know the place in a cleared state only, charge these accounts with exaggeration: but Mr Swinburne thinks them entitled to more respect; for even now, he observes, the air is feverish and dangerous, as the jaundiced faces of the vine-dressers, who have succeeded the Sybils and the Cimmerians in the possession of the temple, most ruefully testify. Boccaccio relates, that, during his residence at the Neapolitan court, the surface of this lake was suddenly covered with dead fish, black and singed, as if killed by some subaqueous eruption of fire.

At present the lake abounds with tench; the Lucrine with eels. The change of fortune in these lakes is singular: In the splendid days of imperial Rome the Lucrine was the chosen spot for the brilliant parties of pleasure of a voluptuous court: now, a slimy bed of rushes covers the scattered pools of this once beau- Averrhoa, beautiful sheet of water; while the once dusky Avernus is clear and serene, offering a most alluring surface and charming scene for similar amusements. Opposite to the temple is a cave usually styled the Sybil's grotto; but apparently more likely to have been the mouth of a communication between Cuma and Avernus, than the abode of a prophetess; especially as the sybil is positively said by historians to have dwelt in a cavern under the Cumae citadel.

AVERRHOA in botany: A genus of the decandra order, belonging to the pentagynia clas of plants; and in the natural method ranking under the 14th order, Gruinales. The calyx has 5 leaves, the petals are 5, opening at top; and the apple or fruit is pentagonal, and divided into 5 cells. There are 3 species, viz. the blimbii, the carambola, and the acida, all natives of the Indies.

The second of these, the carambola, called in Bengal the camrue or camrunga, is remarkable for possessing a power somewhat similar to those species of Mimosa which are termed sensitive plants; its leaves, on being touched, moving very perceptibly. In the mimosa the moving faculty extends to the branches; but from the hardness of the wood, this cannot be expected in the camrunga. The leaves are alternately pinnated, with an odd one; and in their most common position in the day-time are horizontal, or on the same plane with the branch from which they come out. On being touched, they move themselves downward, frequently in so great a degree that the two opposite almost touch one another by their under sides, and the young ones sometimes either come into contact or even pass each other. The whole of the leaves of one pinna move by striking the branch with the nail of the finger or other hard substance; or each leaf can be moved singly, by making an impression that shall not extend beyond that leaf. In this way the leaves of one side of the pinna may be made to move, one after another, whilst the opposite continue as they were; or you may make them move alternately, or in short in any order you please, by touching in a proper manner the leaf you wish to put in motion. But if the impression, although made on a single leaf, be strong, all the leaves on that pinna, and sometimes on the neighbouring ones, will be affected by it. Notwithstanding this apparent sensibility of the leaf, however, large incisions may be made in it with a pair of sharp scissors, without occasioning the smallest motion; nay, it may even be cut almost entirely off, and the remaining part still continue unmoved, when by touching the wounded leaf with the finger or point of the scissors, motion will take place as if no injury had been offered. The reason of this is, that although the leaf be the sensible part which moves, it is in fact entirely passive, and the petiolus is the seat both of sense and action; for although the leaf may be cut in pieces, or squeezed with great force, provided its direction be not changed without any motion being occasioned; yet if the impression on the leaf be made in such a way as to affect the petiolus, the motion will take place. When, therefore, it is wanted to confine the motion to a single leaf, you either touch it so as only to affect its own petiolus, or without meddling with the leaf, touch the petiolus with any small-pointed body, as a pin or knife. By compressing the universal petiolus near the place where a partial one comes out, the leaf moves in a few seconds in the same manner as if you had touched the partial petiolus.

Whether the impression be made by puncture, percussion, or compression, the motion does not instantly follow: generally several seconds intervene, and then it is not by a jerk, but regular and gradual. Afterwards, when the leaves return to their former situation, which is commonly in a quarter of an hour or less, it is so slow a manner as to be almost imperceptible.

On sticking a pin into the universal petiolus at its origin, the leaf next it, which is always on the outer side, moves first; then the first leaf on the opposite side, next the second leaf on the outer, and so on. But this regular progression seldom continues throughout; for the leaves on the outer side of the pinna seem to be affected both more quickly, and with more energy, than those of the inner; so that the fourth leaf on the outer side frequently moves as soon as the third on the inner; and sometimes a leaf, especially on the inner side, does not move at all, whilst those above and below it are affected in their proper time. Sometimes the leaves at the extremity of the petiolus move sooner than several others which were nearer the place where the pin was put in. On making a compression with a pair of pincers on the universal petiolus, between any two pair of leaves, those above the compressed part, or nearer the extremity of the petiolus, move sooner than those under it, or nearer the origin; and frequently the motion will extend upwards to the extreme leaf, whilst below it perhaps does not go farther than the nearest pair. If the leaves happen to be blown by the wind against one another, or against the branches, they are frequently put in motion; but when a branch is moved gently, either by the hand or the wind, without striking against anything, no motion of the leaves takes place.

When left to themselves in the day-time, shaded from the sun, wind, rain, or any disturbing cause, the appearance of the leaves is different from that of other pinnated plants. In the last a great uniformity subsists in the respective position of the leaves on the pinna; but here some will be seen on the horizontal plane, some raised above it, and others fallen under it; and in an hour or so, without any order or regularity which can be observed, all these will have changed their respective positions.

Cutting the bark of the branch down to the wood, and even separating it about the space of half an inch all around, so as to stop all communication by the vessels of the bark, does not for the first day affect the leaves, either in their position or their aptitude for motion. In a branch, which was cut through in such a manner as to leave it suspended only by a little of the bark no thicker than a thread, the leaves next day did not rise so high as the others; but they were green and fresh, and, on being touched, moved, but in a much less degree than formerly.

After sun-set the leaves go to sleep, first moving down so as to touch one another by their under sides: they, therefore perform rather more extensive motion at night of themselves than they can be made to do in the day-time by external impressions. With a convex lens the rays of the sun may be collected on a leaf, so Averroes as to burn a hole in it, without occasioning any motion. But upon trying the experiment on the petiolus, the motion is as quick as if from strong percussion, although the rays be not so much concentrated as to cause pain when applied in the same degree on the back of the hand. The leaves move very fast from the electrical shock, even although a very gentle one.