autumn, in places secure from frost, but also throws out round the mouth of its shell a thick operculum formed from its own saliva; so that it is perfectly secured, and corked up, as it were, from all inclemencies. The cause why the slugs are able to endure the cold so much better than shell-snails is, that their bodies are covered with slime, as whales are with blubber. *

Snails copulate about midsummer; and soon after deposit their eggs in the mould, by running their heads and bodies under ground. Hence, the way to be rid of them is, to kill as many as possible before they begin to breed.

Large, gray, shelless cellar snails, lay themselves up about the same time with those that live abroad: hence, it is plain, that a defect of warmth is not the only cause that influences their retreat.

SNAKE'S SLOUGH.

There the snake throws her enamel'd skin.

SHAKESPEARE's Mids. Night's Dream. About the middle of this month (September) we found, in a field near a hedge, the slough of a large snake, which seemed to have been newly cast. From circumstances, it appeared as if turned wrong side outward, and as drawn off backward, like a stocking, or woman's glove. Not only the whole skin, but scales from the very eyes, are peeled off, and appear in the head of the slough like a pair of spectacles. The reptile, at the time of changing his coat, had entangled himself intricately in the grass and weeds, so that the friction of the stalks and blades might promote this curious shifting of his exuviæ.

It would be a most entertaining sight, could a person be an eye-witness to such a feat, and see the snake in the act of changing his garment. As the convexity of the scales of the eyes in the slough is now inward, that circumstance alone is a proof that the skin has been turned: not to mention that now the present inside is much darker than the outer. If you look through the scales of the snake's eyes from the concave side, viz. as the reptile used them, they lessen objects much. Thus it appears, from what has been said, that snakes crawl out of

Slugs have the property of spinning a slimy thread, whereby they can let themselves down from a height in the manner of spiders. —ED.

the mouth of their own sloughs, and quit the tail part last, just as eels are skinned by a cook maid. While the scales of the eyes are growing loose, and a new skin is forming, the creature, in appearance, must be blind, and feel itself in an awkward, uneasy situation. *

OBSERVATIONS ON VEGETABLES.

TREES, ORDER OF LOSING THEIR LEAVES.

ONE of the first trees that become naked is the walnut; the mulberry, the ash, especially if it bears many keys, and the horse-chestnut come next. All lopped trees, while their heads are young, carry their leaves a long while. Apple trees and peaches remain green very late, often till the end of November; young beeches never cast their leaves till spring, till the new leaves sprout and push them off: in the autumn, the beechen leaves turn of a deep chestnut colour. Tall beeches cast their leaves about the end of October.

SIZE AND GROWTH. -Mr Marsham of Stratton, near Norwich, informs me by letter thus:-"I became a planter early; so that an oak which I planted in 1720 is become now, at one foot from the earth, twelve feet six inches in circumference, and, at fourteen feet, (the half of the timber

* I have seen many sloughs, or skins of snakes, entire, after they have cast them off; and, once in particular, I remember to have found one of these sloughs so intricately interwoven amongst some brakes, that it was with difficulty removed without being broken : this undoubtedly was done by the creature to assist in getting rid of its encumbrance.

I have great reason to suppose that the eft, or common lizard, also casts its skin, or slough, but not entire like the snake; for, on the 30th of March, 1777, I saw one with something ragged hanging to it, which appeared to be part of its old skin.-MARKWICK.

It has been found by Pallas, that, after leeches have been used for medicinal purposes, they are most reproductive. He puts them into a box with argillaceous earth, six inches deep, at any time from the middle of August till the end of September. In five months, cocoons will be found, each containing twelve individuals. The cocoons are, on the outside, light, porous, and wooly, to keep out moisture and regulate the temperature. On the inside they are fibrous and dense, enclosing a thin inultilocular pellicle, which contains germs. -ED.

length,) is eight feet two inches. So, if the bark were to be measured as timber, the tree gives one hundred and sixteen and a half feet, buyer's measure. Perhaps you never heard of a larger oak, while the planter was living. I flatter myself that I increased the growth by washing the stem, and digging a circle, as far as I supposed the roots to extend, and by spreading sawdust, &c. as related in the Phil. Trans. I wish I had begun with beeches, (my favourite trees, as well as yours ;) I might then have seen very large trees of my own raising. But I did not begin with beech till 1741, and then by seed; so that my largest is now at five feet from the ground, six feet three inches in girth, and, with its head, spreads a circle of twenty yards diameter. This tree was also dug round, washed, &c. Stratton, 24th July, 1790."

The circumference of trees planted by myself, at one foot from the ground, (1790 :)

The great oak in the Holt, which is deemed by Mr Marsham to be the biggest in this island, at seven feet from the ground, measures, in circumference, thirty-four feet. It has, in old times, lost several of its boughs, and is tending to decay. M Marsham computes, that, at fourteen feet length, this oak contains one thousand feet of timber.

It has been the received opinion, that trees grow in height only by their annual upper shoot. But my neighbour, over the way, whose occupation confines him to one spot, assures me, that trees are expanded and raised in the lower parts also. The reason that he gives is this: the point of one of my firs began, for the first time, to peer over an opposite roof at the beginning of summer; but, before the growing season was over, the whole shoot of the year, and three or four joints of the body beside, became visible to him, as he sits on his form in his shop. According to this supposition, a tree may advance in height considerably, though the summer shoot should be destroyed every year.

FLOWING OF SAP.-If the bough of a vine is cut late in the spring, just before the shoots push out, it will bleed considerably; but, after the leaf is out, any part may be taken

off without the least inconvenience. So oaks may be barked while the leaf is budding; but, as soon as they are expanded, the bark will no longer part from the wood, because the sap that lubricates the bark, and makes it part, is evaporated off through the leaves.*

RENOVATION OF LEAVES.-When oaks are quite stripped of their leaves by chaffers, they are clothed again, soon after midsummer, with a beautiful foliage; but beeches, horsechestnuts, and maples, once defaced by those insects, never recover their beauty again for the whole season.

ASH TREES. Many ash trees bear loads of keys every year; others never seem to bear any at all. The prolific ones are naked of leaves, and unsightly; those that are steril abound in foliage, and carry their verdure a long while, and are pleasing objects. †

BEECH. Beeches love to grow in erowded situations, and will insinuate themselves through the thickest covert, so as to surmount it all are therefore proper to mend thin places in tall hedges.

SYCAMORE.-May 12.-The sycamore, or great maple, is in bloom, and, at this season, makes a beautiful appearance, and affords much pabulum for bees, smelling strongly like honey. The foliage of this tree is very fine, and very ornamental to outlets. All the maples have saccharine juices.

GALLS OF LOMBARDY POPLAR.-The stalks and ribs of the leaves of the Lombardy poplar are embossed with large tumours of an oblong shape, which, by incurious observers, have been taken for the fruit of the tree. These galls are full of small insects, some of which are winged, and some not.

A correspondent, in Loudon's Magazine, proposes a theory of the ascent of sap. "The theory which I wish to prove," says he, "is the following: The sap, in its descent in the stem, becomes deprived of some of its constituents, more especially of its aqueous part: this deprivation is effected by the vital principle of the plant decomposing the aqueous parts, and assimilating the resulting gases to its own constituents. the assimilation takes place, a partial vacuum is formed by the change of gas to a solid form; and this vacuum is immediately filled with sap rushing into it, according to the well-known law of the tendency of fluids to rush into any cavity deprived of the presence of air.".

ED.

As

+ Great irregularity exists in the fall of the leaf in ash trees. Many trees will already have cast their foliage, when others in the same hedge-row seem scarcely to have at all suffered from the chilling influence of autumnal winds. This cannot be attributed to difference of exposure, as we have observed them almost alternately with each other, in full leaf and denuded, for miles along a road side. .En.

The parent insect is of the genus of cynips. Some poplars in the garden are quite loaded with these excrescences.*

CHESTNUT TIMBER.-John Carpenter brings home some old chestnut trees, which are very long; in several places, the woodpeckers had begun to bore them. The timber and bark of these trees are so very like oak, as might easily deceive an indifferent observer; but the wood is very shakey, and, towards the heart, cup-shakey, (that is to say, apt to separate in round pieces like cups,) so that the inward parts are of no use. They are bought for the purpose of cooperage, but must make but ordinary barrels, buckets, &c. Chestnut sells for half the price of oak; but has sometimes been sent into the king's dock, and passed off instead of oak.

LIME BLOSSOMS.- Dr Chandler tells, that, in the south of France, an infusion of the blossoms of the lime tree, (tilia,) is in much esteem as a remedy for coughs, hoarsenesses, fevers, &c.; and that, at Nismes, he saw an avenue of limes that was quite ravaged and torn in pieces by people greedily gathering the bloom, which they dried and kept for these purposes.

Upon the strength of this information, we made some tea of lime blossoms, and found it a very soft, well flavoured, pleasant, saccharine julep, in taste much resembling the juice of liquorice.

BLACKTHORN. This tree usually blossoms while cold north-east winds blow; so that the harsh rugged weather obtaining at this season is called, by the country people, blackthorn winter.

IVY BERRIES.-Ivy berries afford a noble and providential supply for birds in winter and spring; for the first severe frost freezes and spoils all the haws, sometimes by the middle of November. Ivy berries do not seem to freeze.

HOPS.-The culture of Virgil's vines corresponded very exactly with the modern management of hops. I might instance in the perpetual diggings and hoeings, in the tying to the stakes and poles, in pruning the superfluous shoots, &c.; but lately, I have observed a new circumstance, which was, a neighbouring farmer's harrowing between the rows of hops

* Mr David Don, a botanist of distinguished talents, has discovered, that, on detaching the spiral vessels from vigorous young shoots of herbaceous plants, they frequently become violently agitated; the motion con.. tinues for some seconds, and may be somewhat similar to that of the heart of animals under similar circumstances. These vessels abound in the stems of the urtica nivea, of centaurea atro-purpurea, and of the malvaca.-ED.