disease incident to trees, proceeding chiefly from the nature of the soil. It makes the bark rot and fall. If the canker be in a bough, cut it off; in a large bough, at some distance from the stem; in a small one, close to it: but for over-hot strong ground, the ground is to be cooled about the roots with pond-mud and cow-dung.

Canker, among farriers, See Farriery, § xliv. 2.

Canna, Indian cane; a genus of the monogynia order, belonging to the monandria class of plants.

Species. 1. The indica, or common broad-leaved flowering cane, is a native of both Indies; the inhabitants of the British islands in America call it Indian foot, from the roundness and hardness of the seeds. It hath a thick, fleshy, tuberous root, which divides into many irregular knobs; it sends out many large oval leaves, without order. At their first appearance the leaves are like a twisted horn, but afterwards expand, and are near a foot long, and five inches broad in the middle; lessening gradually to both ends, and terminated in a point. The stalks are herbaceous, rising four feet high, and are encompassed by the broad leafy footstalks of the leaves; at the upper part of the stalk the flowers are produced in loose spikes, each being at first covered with a leafy hood, and turns to a brown colour. The flowers are succeeded by a fruit or capsule, oblong, rough, and crowded with the three-cornered empalement of the flower which remains. When the fruit is ripe, the capsule opens lengthwise into three cells, filled with round, shining, hard, and black seeds. 2. The latiflora, with a pale red flower, is a native of Carolina, and some other northern provinces of America. 3. The glauca, with a very large flower, is a native of South America. 4. The lutea, with obtuse, oval leaves, is less common in America than the other sorts. 5. The coccinea, hath larger leaves than any of the other species, and the stalks rise much higher. The flowers are produced in large spikes; and are of a bright crimson, or rather scarlet colour.

Culture. These plants must always be kept in pots of rich earth, to be moved to shelter in winter. They are propagated by seeds sown on a hot-bed in the spring; and in summer, when the plants are a little advanced in growth, prick them separately in small pots of rich earth, plunging them also in the hot-bed, giving shade, water, and fresh air; to which last harden them by degrees, till they bear it fully. In October they must be removed into a very good stove or greenhouse.

Cannabis, hemp; a genus of the pentandria order, belonging to the dioecia class of plants. Of this there is but one species, viz. the sativa. This is pro- pagated in the rich fenny parts of Lincolnshire in great quantities, for its bark, which is useful for cordage, cloth, &c. and the seeds abound with oil. Hemp is always sown on a deep, moist, rich soil, such as is found in Holland, Lincolnshire, the fens of the island of Ely, where it is cultivated to great advantage, as it might be in many other parts of England where there is a soil of the same kind; but it will not thrive on clayey or stiff cold land. The ground on which hemp is designed to be sown should be well ploughed, and made very fine by harrowing. About the middle of April the seed may be sown; three bushels is the usual allowance for an acre, but two are sufficient. In the choice of the seed, the heaviest and brightest coloured should be preferred; and particular care should be had to the kernel of the seed. For the greater certainty in this matter, some of the seeds should be cracked, to see whether they have the germ or future plant perfect: for, in some places, the male plants are drawn out too soon from the female; i.e. before they have impregnated the female plants with the farina; in which case, though the seeds produced by these females may seem fair to the eye, yet they will not grow *, according to the doctrine of Linnæus. When the plants are come up, they should be hoed out in the same manner as is practised for turnips, leaving them two feet apart; observe also to cut down all the weeds, which, if well performed, and in dry weather, will destroy them. This crop, however, will require a second hoeing, in about six weeks after the first; and, if this is well performed, the crop will require no further care. The first season for pulling hemp is usually about the middle of August, when they begin to pull what they call the flax hemp, being that which is composed of the male plants; but it would be the much better method to defer this for a fortnight or three weeks longer, until those male plants have fully shed their farina or dust, without which the seeds will prove only empty hulls. These male plants decay soon after they have shed their farina. The second pulling is a little after Michaelmas, when the seeds are ripe. This is usually called karle hemp, and consists of the female plants which were left. This karle hemp is bound in bundles of a yard compass, according to statute measure, which are laid in the sun for a few days to dry; and then it is stacked up, or houseted, to keep it dry till the seed can be threshed out. An acre of hemp, on a rich soil, will produce near three quarters of seed, which, together with the unwrought hemp, is worth from six to eight pounds. Hemp is esteemed very effectual for destroying weeds; but this it accomplishes by impoverishing the ground, and thus robbing them of their nourishment; so that a crop of it must not be repeated on the same spot.—From the leaves of hemp pounded and boiled in water, the natives of the East Indies prepare an intoxicating liquor of which they are very fond. The plant, when fresh, has a rank narcotic smell; the water in which the stalks are soaked, in order to separate the tough rind for mechanic uses, is said to be violently poisonous, and to produce its effects almost as soon as drank. The seeds also have some smell of the herb, and their taste is unctuous and sweetish: they are recommended, boiled in milk, or triturated with water into an emulsion, against coughs, heat of urine, and the like. They are also said to be useful in incontinence of urine, and for restraining venereal appetites; but experience does not warrant their having any virtues of that kind.