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selves into the air, when they are no longer necessary for supplying the place of leaves. The petals of flowers, also, with their stamens and pistils, wither and fall when the formation of the seed has been effected; and when at last the fruit has arrived at maturity, it likewise separates from the parent plant or tree, and drops to the ground.
I have already remarked, that the duration of the stem and branches is very different in different plants. The longevity of some trees is very remarkable. The following notice is taken from the article Vegetable Physiology,' in the Supplement to the Encyclopædia Britannica. "The Gentleman's Magazine, for 1762, contains an account of the age of a chestnut-tree, then growing at Tamworth, in Staffordshire. This tree, it is said, was, at that period, probably the oldest, and certainly one of the largest, in England, being fifty-two feet in circumference. Its period of rising from the nut may be fixed at the year 800, in the reign of King Egbert. From that date to the reign of King Stephen is 335 years, at which time it was fixed on as a boundary or landmark, and called, by way of distinction, 'the Great Chestnut Tree of Tamworth.' From the first year of Stephen (anno 1135) to 1762, is 627 years, so that its entire age at that period was 962 years. It bore nuts in 1759, from which young trees were raised."
It is probable that some kinds of trees, which are natives of more genial climates, are even longer lived than the great tree of Tamworth. It is interesting to know, that there are olive trees of a most venerable age now growing in the garden of Gethsemane, near the bottom of the Mount of Olives, which are supposed to have sprung from the roots of those that existed there during our Saviour's life. The conjecture is founded on the known longevity of the olive. The historical fact, that, during the siege of Jerusalem, Titus cut down all the trees in the neighborhood of that devoted city, seems to preclude the possibility of their being the very trees whose boughs shaded the Divine Sufferer in his agony; but yet there is something which wonderfully excites the imagination, in the fact, that, after the lapse of more
than seventeen centuries, scions of those venerable olives should still be in existence to mark the sacred spot.*
PROGRESS OF VEGETATION IN THE CORN-PLANTS.
HAVING now arrived at the season when the different kinds of corn have reached maturity, it may be proper to look back on the various steps by which the vegetative process has been completed. În this retrospect, we shall constantly be reminded of the Creative Intelligence and superintending care of the God of the Seasons.
I have, in the Spring' volume, taken some notice of the nature and productive qualities of cultivated grain, as well as of the history of the various species, as articles of agriculture. What I intend to do, at present, is to trace the seed in the progress of its developement, from the period in which it is thrown into the prepared soil, till that in which it becomes ripe for the sickle. Of all the kinds of corn raised in Europe, that of wheat is not only the most valuable, but the longest attached to the soil before it arrives at full perfection. I shall confine myself, therefore, to this species of the cereal plants, premising, that the physiological history of wheat is, with some slight exceptions, nearly identical with that of its kindred tribes.
Wheat is generally sown in the last weeks of autumn, so as to pass through the first important steps of the vegetative process before the severity of winter sets in. In its earliest growth there is little peculiar. Like other seeds, whose developement has been described in the volume on 'Spring,' it consists of a bud containing the embryo
* [Chateaubriand says some of these very trees can unquestionably be traced to the time of the Eastern empire. In Turkey, every olivetree, found standing by the Mussulmans, when they conquered Asia, pays one medine to the treasury; every one planted since the conquest, is taxed half its produce. Now, eight of these trees, very large and old, are still charged only eight medines.-AM. ED.]
of the future root and plumale,* wrapt up in integuments, and lying between, but at one end of the cotyledons, which serve as its first nourishment. When the seed has been in the ground for about two days, it begins to swell, and the juices contained in the cotyledons, being communicated to the bud, produce in it the first vegetative motions, and cause it to shoot out its roots and plumale. The root is at first wrapt up in a kind of purse, through which it forces its way. Two other roots spring forth in a lateral direction, within a few days, and burst through the texture which covered them, now softened by the moisture of the earth in which they are buried. Each of the roots is shagged with a number of fibres, which closely twine about the particles of earth presented to them in their progress, and extract from them whatever is capable of nourishing the young plant in conjunction with the fluids which it still derives from the inward substance of the seed.
Meanwhile, the plumale shoots upwards in as direct a line as circumstances will admit, protected by a little tegument, which withers away when its services are no longer required. In favorable circumstances, the corn will begin, about the sixth or seventh day, to push its verdant point through the surface of the earth. This feeble stem is nothing more than a bundle of leaves folded over each other, and around the delicate embryo which is to form the future spike. The first leaf of this packet opens a little towards the point, but its lower part is always rolled up in the hard covering from whence it springs. In a few days after the stem emerges to the light, the parent seed, which has been gradually giving out its milky juices for the nourishment of the plant, shrivels up and begins to decay.
If we clear away the tegument of the seed, and retrench the matter from whence the roots have shot, along with the roots themselves, as well as that which emitted the plumale, we shall have nothing left but the bundle of green leaves already mentioned, which contains the real These leaves, when carefully and skilfully un* [The plumale, or plumula, is the upper or leafy part of the embryo plant.-AM. ED.]
folded, will display the first rudiments of four tubes growing out of each other, and attached by knots. These compose the stem, and, at the highest extremity of the upper tube, the bud of the spike will appear. From the first knot, which is nearest to the roots, a leaf springs forth, and performs the office of a covering to the second tube. Another leaf likewise rises from the second knot, and wraps itself round the third tube. The third knot produces another leaf, which encloses the fourth tube, together with the embryo spike. The space between the first and second knot, nearest the roots, is then much larger than the interval that separates the second knot from the third. The spike rising, as I have already said, at the upper extremity of the fourth tube, may, even at this period, be easily distinguished by the roundness and transparency of its little grains, which resemble so many pearls.
In this state, the plant braves all the severity of winThe spike, secure in its fourfold integuments, and in that mysterious power of the vital principle, which, if it does not actually generate heat, at least resists the influence of cold, endures without injury the fury of the tempest, the pelting of the heavy rains, and those sudden alternations of temperature, to which the season is liable. The leaves, which so carefully embrace it, preserve their verdure, and, in every favorable interval of warmth, continue to flourish and expand. On the return of spring, should the vegetation appear to be prematurely luxuriant, the husbandman fearlessly admits to the field a flock of sheep, which, by nibbling off the points of the foliage, afford greater nourishment to the stem, and by giving the vegetative power a new direction, cause the wheat to tiller, that is, produce new shoots, and occasion a more abundant produce.
As the season becomes more genial, the stem shoots vigorously upwards, abandoning the leaves, which are no longer necessary for its covering the spike itself enlarges, and casts aside its integuments. The different lodgements that are to contain the future grains, begin to be enlarged; and at length they unfold two kinds of pistils, to receive the powder from the knot of chives
which appear in a higher situation, and whose influence. is necessary to impart fertility to the buds.
During this stage of the vegetation, a considerable change takes place in the plant. The foliage and the first leaves, which are no longer necessary for the protection of the seed, fall down, lose their juices, and wither away. The whole vital power seems now to be required for the nourishment of the stem, and through the stem, for that of the spike; which latter, indeed, is obviously the main design of the whole process. They are therefore concentrated in this important object.
There is another circumstance in the formation of the stem, which is too admirable to be passed over in silence. It is one of the conditions which Creative Wisdom has impressed upon this plant, that it shall rise to a considerable height, and thus furnish a useful straw to the husbandman; while, by this means, it receives the advantage of the free admittance of the air, and full exposure to the genial rays of the sun, instead of being overborne, as it might otherwise have been, by the cumbersome luxuriance of an inferior vegetation. This condition, however, required peculiar qualities in the stem. That it might occupy little space in the field, and thus admit of as much nourishing grain as possible in a given quantity of ground, it is of importance that the stalk should be slender; and, accordingly, it does not extend to more, on an average, than two-twelfths of an inch in diameter, while it rises to the height of four or five feet, and even sometimes more. How does it happen, that so long and thin a stalk should be able to support a spike heavy with grain? The contrivance by which this is secured, is not a little remarkable. In the first place, the stem is a hollow tube,—a form which can easily be demonstrated to be the most advantageous for strength and for resisting injury; and, in the next place, four knots of a solid substance, resembling firm bands, give it strength, without unduly diminishing its flexibility. So constituted, it is capable of bending without being broken under all common gales of wind, and even under the force of impetuous blasts; the knots enabling it to recover its upright position in the returning calm. It is beautiful to see the undulations of a field of