And now Nature doctors the wound made by the leaf's fall. The broken ends of the bundles of fibres and vessels left at the scar are covered (in many trees) with a protecting gum, and a little later they are encompassed by the growth of the cork-seal, and the healing of the scar is complete.
The falling foliage of the horse-chestnut leaves scars large enough to show clearly the marks of Nature's surgery. The cork-seal, which is much in evidence, has a horseshoe-shaped outline, and the slightly projecting ends of the fibro-vascular bundles, overlaid by a dark, glistening gum, suggest the horseshoe-nails (Fig 99b).
What falls from the bough in autumn is little more than the dead skeleton of the summer leaf - mere dry skin, empty cells, and stringy fibre. Almost all the living substances which once filled the leaves were withdrawn from them before they fell, and are now safely stored away in trunk and boughs. Professor Von Sachs, author of the "Physiology of Plants," has observed that in autumn the cell-contents of the leaves about to fall are changed into soluble substances, and these are conveyed to the permanent parts of the plant. The protoplasm, or clear leaf-jelly, disappears, and so do the little green chlorophyll corpuscles which float in it.
"I was able," says Professor Von Sachs, "by microchemical methods, to follow distinctly the travelling of the materials (especially of the starch) out through the tissue of the leaf-stalk into the shoot-axes. Moreover, the ash-analyses of summer leaves, compared with those of autumn ones, show that the most valuable mineral constituents of the leaves, especially the potash and phosphoric acid, also pass out, through the leaf-stalks, back into the parts of the bough which survive the winter.
By time the leaves fall the cells of their tissues contain little else than a few mineral crystals, but those of the branch, just under the cork layer, are rich in starch and protoplasm. And when the sun comes back to us from the South these living principles of the dead leaves are pushed up anew into the April buds, and help to form the tender foliage of another year.
Fig. 99b. - Leaf-scar of the horse-chestnut, showing the cork-seal studded with theblackened ends of fibro-vas-cular bundles. (Magnified).
When Nature begins to empty the leaf-cells in autumn the little green disks of chlorophyll "lose their normal outline, assume irregular shapes, and their coloring matter," says Professor Von Sachs, "undergoes changes." The crimson, purple, and golden-green leaves of early spring are leaves into which chlorophyll has not yet come. The crimson, purple, and yellow leaves of autumn are leaves in which chlorophyll has lost its green color and its active life. The splendor of the October woods was prophesied in April, but the leaves which mutely foretold it were too tiny and their colors were too evanescent to catch the attention of busy people. And the autumn glory, when it comes, more than fulfils the little hints and half-promises which the trees give us in spring.
Some plants, the annuals, never awaken from their winter sleep. One summer is their span of life. But these are but a small proportion of the vegetable world, and even these, by the time summer is ended, have attained full growth, blossomed, and set and ripened their seed. They are fading, not because frost has nipped them, but because old age has come upon them and their life-work is done. Dying, they bequeath their goods to their descendants and natural heirs. The materials drawn out of their leaves go into the ripening seeds, to be used, next spring, in the nurture of the seedlings. These annuals, after their seeds are ripe, are little else than an empty network of dry dead cells. The sweet alyssum and mignonette are metamorphosed into what he who clears up the garden calls "straw," their juices having gone to fill out the seeds, which are now ripe and ready, in innumerable little pockets, green or brown.
In scientific botany the little pockets of the fruit, which hold the ripened seed, are known as "loculi." If we cut an apple across we will see five of these loculi arranged in the form of a star. They have transparent, horny, brownish walls and in each is a seed or two.
Another use of the term loculi is familiar to the classicist and to the antiquarian. In the catacombs of Rome there are wall-spaces all honeycombed with niches designed to hold the bodies of the dead, or the urns containing their ashes. And each of these is called a "loculus".
This twofold use of the word may be a mere phililogical accident. But it suggests to our minds the thought which the botanist who first applied the term to the seed-case had, perhaps, in his - the analogy used by the apostle in teaching that the dead body, sown with tears, is as the seed, and the soul is as the germ, which lives on in transfigured beauty when "God giveth it a body, as it hath pleased Him".
Where each flower has perished, in garden or field, there is a seed, or more probably a pocket filled with seeds, each a prophecy and a pledge of the flowers which will gladden the earth next year. And each leaf, falling, leaves behind it a bud, from which a cluster of leaves or a cluster of flowers will unfold.
All things have their price, both in the spiritual and in the natural world. Without the torpor of winter, the freshness and gladness of spring could never be. Semi-tropic lands which escape the one miss the other. Only to lands which have known "the long dark nights and the snow" comes the ecstasy of the northern spring, when skies growing daily brighter, and earth awakening under them with joy foretell to us the "new heavens and the new earth" wherein shall dwell righteousness.