The root is the organ through which food is conveyed from the earth into the plant, and is the part which is soonest developed, increasing in length by the addition of new matter at its point, much as an icicle by the constant superposition of layer over layer, with this difference, that the icicle is augmented by the addition of matter from without, while the root lengthens by the perpetual creation of new matter from within. Being furnished with the power of perpetually adding new living matter to their points, they are thus enabled to pierce the solid earth in which they grow, shifting their mouths in search of fresh pasturage; hence the expression, "You may feed your trees as well as your chickens." A Populus monilifera, Canadian poplar, has been known to send a root thirty feet horizontally, including its dip beneath a wall, and then to have passed into an old deep well to the depth of eighteen feet. A deciduous cypress-root, eleven feet long, passed nearly to that length without division, in search of water.

Willows exhibit even greater desire to travel in search of nourishment.

It is not merely in length that the root increases, or else all roots would be mere threads; they also augment in diameter, simultaneously with the stem. Neither is it by an embryo alone that roots are formed. A plant once in a state of growth, has the power of producing roots from various parts, especially from leaves and stems. A Spanish chestnut, between ninety and one hundred years old, was cut down in 1849. With the exception of its foliage, which always had a yellowish sickly tinge, there was scarcely anything else that indicated decay. Its trunk seemed perfectly sound, with healthy annual shoots. No sooner had the workmen commenced cutting, than it was discovered that for ten feet high, as much as two-thirds of the bark round the trunk was dead and reduced to a mere shell. On removing this thin covering, the sap-wood was found to have become a mass of decayed vegetable matter, through which a complete network of roots passed to the ground, as represented in the cut, and extended themselves for a considerable distance from the main stem; some of these roots were about the size of an ordinary walking-stick. Cases of remarkable roots are familiar to observers.

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Fig. l.

An Episcia bicolor happened to have its leaves injured by an accident, which cut the midrib and a portion of leaf on both sides of it; after a certain time, the wound healed, the part next the base of the leaf remaining the same thickness as before the injury, while the edge of the outer portion gradually thickened, and developed a small bud close to the midrib, Fig. 2, from which a number of minute fibrous roots issued, and eventually a stem anil leaves, as represented in the sketch. As the plant increased, the old leaf gradually became exhausted, and perished altogether as soon as the young leaves gained the ascendency and de-prived it of the scanty means that had previously supported it. Similar instances are familiar, not the least interesting of which is that of a broken celery-leaf, which sent out roots from the lowermost of its wounded edges.

In general, roots have no buds, and are, therefore, incapable of multiplying the plant to which they belong. But it constantly occurs, in some species, that they have the power of forming what are called adventitious buds; and, in such cases, they may be employed for purposes of propagation. There is no rule by which the power of a plant to generate such buds can be judged of; experiment is, therefore, necessary, in all cases to determine the point. Exceptions are found in the Moutan peony, in the plum-tree, or the Pyrus (Cydonia) japonica, which may be increased with great facility by small bits of the roots being inserted in a shady border, and covered with a hand-glass; but in none of them does the power reside in the same degree as in the Japan Anemone. If a root be taken after flowering, it will be found to resemble brown cord, divided into a great number of ramifications, as represented in the cut. Upon its surface will be perceived a multitude of white conical projections, sometimes growing singly, sometimes in clusters, and occasionally producing scales upon their sides. A magnified view of these bodies is shown in Fig. 3, a.

They are young buds, every one of which, if cut from the parent, will grow and form a young plant in a few weeks, every fragment of the plant being productive.

It is certain that vitality is stronger in the roots than in any other part of a plant. Live roots have been found in land many years after the trunks to which they belonged had been destroyed. Mr. Knight gives some curious particulars in his Physiological Papers, pp. 83, 325.

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Fig. 2.

It has been confidently asserted that roots are the organs by which plants rid themselves of the secreted matter which is either superfluous or deleterious to them. Correct experiments, however, have shown that such results are only obtained when roots are lacerated, and that they have no greater power of excreting matter than other parts of a plant. The theory of root-excretions was sustained by Liebig, but it is now abandoned. - Pof. Lindley.

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Fig. 3.