the act of multiplying the kind. See Generation.

PROPAGATION of Plants. The most natural and the most universal way of propagating plants is by seeds. See Plants, and Natural History, p. 654. But they may also be propagated by sets, pieces, or cuttings, taken from the parent plant. Willows are very easily propagated by sets; such as rise to be considerable timber trees being raised from sets 7 or 8 feet long, sharpened at their larger ends, which are thrust into the ground by the sides of ditches, on the banks of rivers, or in any moist soil. The fallow trees are raised from sets only 3 feet long. The plane tree, mint, &c. may be propagated in the same way. In providing the slips, sprigs, or cuttings, however, care must be taken to cut off such branches as have knots or joints 2 or 3 inches beneath them; small top sprigs of 2 or 3 years growth are the best for this operation. Plants are also propagated by parting their roots, each part of which, properly managed, sends out fresh roots. Another mode of propagating plants is by layering or laying the tops of the branches in the ground.

The method of layering is this: Dig a ring-trench round the stool, of a depth suitable to the nature of the plant; and having pitched upon the shoots to be layered, bend them to the bottom of the trench (either with or without plashing, as may be found most convenient), and there peg them fast; or, putting some mould upon them, tread them hard enough to prevent their springing up again—fill in the mould—place the top of the layer in an upright posture, treading the mould hard behind it; and cut it carefully off above the first, second, or third eye. Plants are also propagated by their bulbs.

The number of vegetables that may be propagated from an individual is very remarkable, especially in the most minute plants. The annual product of one seed even of the common mallow has been found to be no less than 200,000; but it has been since proved, by a strict examination into the more minute parts of the vegetable world, that so despised a plant as the common wall mallow produces a much more numerous offspring. In one of the little heads of this plant there have been counted 13,824 seeds. Now allotting to a root of this plant eight branches, and to each branch six heads, which appears to be a very moderate computation, the produce of one seed is $6 \times 13,824 = 82,944$; and $8 \times 82,944$, gives 663,552 seeds as the annual produce of one seed, and that so small that 13,824 of them are contained in a capsule, whose length is but one ninth of an inch, its diameter but one 23d of an inch, and its weight but the 13th part of a grain.

For the propagation or culture of particular plants, see Agriculture, Part II, sect. 3, p. 288, and Husbandry.