DO VARIETIES OF FRUIT RUN OUT?
Is there such similarity between animals and vegetables, in their organic structure, development and functions, as to make it safe to reason upon the properties of the one from the known properties of the other?
It is admitted that the lowest forms of vegetable existence are extremely difficult to be distinguished from a corresponding form of animal existence. As we approach the lower confines of the vegetable kingdom, flowers, and of course, seeds, disappear. The distinction between leaves and stem ceases; and, at last, the stem and root are no longer to be separated, and we find a mere vegetable sheet or lamina whose upper surface is leaf and whose lower surface is root. In a corresponding sphere, animal existence is reduced to its simplest elements. Whatever resemblances there are in the lowest and rudimentary forms of vegetable and animal life, it cannot be doubted that when we rise to a more perfect organization, the two kingdom become distinct and the structure and functions of each are in such a sense peculiar to itself, that he will grossly misconceive the truth who supposes a structure or a function to exist in a vegetable, because such structure or function exists in an animal, and vice versâ. To be sure, they resemble in generals but they differ in specials. Both begin in a seminal point but the seed is not analogous; both develop—but not by an analogous growth; both require food, but the selection, the digestion and the assimilation are different. The mineral kingdom is the lowest. Out of it, by help of the sun and air, the vegetable procures its materials of growth; in turn the vegetable kingdom is the magazine from which the animal kingdom is sustained; to each, thus the soil contains the original elements; the vegetable is the chemical manipulator, and the animal, the final recipient of its products. The habit of reasoning from one to the other, of giving an idea of the one by illustrations drawn from the
other, especially in popular writings, will always be fruitful of misconceptions and mistakes.
The next idea set forth in the paragraph which we review, is, the essential dissimilarity of buds and seeds. The writer thinks that a plant from a seed is a new organization, but a plant from a bud or graft (which is but a developed bud) is but a continuation of a previous plant. With the exception of their integuments, a bud and a seed are the same thing. A seed is a bud prepared for one set of circumstances, and a bud is a seed prepared for another set of circumstances—it is the same embryo in different garments. The seed has been called, therefore, a “primary bud,” the difference beng one of condition and not of nature.
It is manifest, then, that the plant which springs from a bud is as really a new plant as that which springs from a seed; and it is equally true, that a seed may convey the weakness and diseases of its parent with as much facility as a bud or a graft does. If the feebleness of a tree is general, its functions languid, its secretions thin, then a bud or graft will be feeble,—and so would be its seed; or if a tree be thoroughly tainted with disease, the buds would not escape, nor the tree springing from them—neither would its seed, or a tree springing from it. A tree from a bud of the Doyenne pear is just as much a new tree as one from its seed.
The idea which we controvert has received encouragement from the fact, that a bud produces a fruit like the parent tree, while, oftentimes, a seed yields only a variety of such fruit. But, it is probable that this is never the case with seeds except when they have been brought into a state of what Van Mons calls variation. In their natural and uncultivated state, seeds will reproduce their parent with as much fidelity as a bud or a graft.
The liability of a variety to run out, when propagated by bud or graft, is not a whit greater than when propagated by seed, in so far as the nature of the vegetable is concerned.
But it is true that the conditions in which a bud grows render it liable to extrinsic ills not incidental to a plant springing from seed. A seed, emitting its roots directly into the earth, is liable only to its own ills; a bud or graft emitting roots, through the alburnum of the stock on which it is established, into the earth, is subject to the infirmities of the stock as well as to its own. Thus a healthy seed produces a healthy plant. A healthy bud may produce a feeble plant, because inoculated upon a diseased branch or stem.
Instead of a limitation in their nature, there is reason to suppose that trees might flourish to an indefinite age were it not for extrinsic difficulties. A tree, unlike an animal, is not a single, simple organization, it is rather a community of plants. Every bud separately is an elementary plant, capable, if disjoined from the branch, of becoming a tree by itself. In fact, each bud emits roots, which, uniting together, go down upon a common support (the trunk) and enter the earth, and are there put in connection with appropriate food. Every fibre of root may be traced upward to its bud from which it issued.
In process of time, the elongation of the trunk exposes it to accidents; the branches are subject to the force of storms; in proportion as the distance from the roots increases, and the longer the passages through which the upper sap, or downward elaborated sap travels, the more liabilities are there to stoppage and injury. The reason of decline in a tree is not to be looked for in any exhaustion of vital force in the organization itself, but it is to be found in the immense surface and substance exposed to the wear and tear of the elements.
It would seem, if this view be true, that no bounds can be placed to the duration of perennial plants, if, by any means, we could diminish their exposure, by reducing their expansion, by keeping them within a certain sphere of growth. Now this is exactly what is accomplished by budding.
A bud, far removed on the parent stock from the root and connected with it through a long trunk, is inoculated upon a new stock. It now grows with a comparatively limited exposure to interruption or accident. The connection with the soil is short and direct.
In this manner a variety of fruit may be perpetuated to all generations, if the laws of vegetable health be regarded in the process. Healthy buds, worked upon healthy stocks and planted in wholesome soil, will make healthy trees; and from these another generation may proceed, and from these another. By a due regard to vegetable physiology, the Newtown Pippin, and the Seckle Pear, may be eaten two thousand years hence, provided, always, that expounders of prophesy will allow us the use of the earth so long for orchard purposes. A disregard of the laws of vegetable physiology in the propagation of varieties, will, on the other hand, rapidly deteriorate the most healthy sort. There is no clock-work in the branches of the tree, which finally runs down past all winding up; there is no fixed quantity of vitality, which a variety at length uses up, as a garrison does its bread. Plants renew themselves and every year have a fresh life, and, in this respect, they differ essentially from all forms of animal existence. Any one tree may wear out; but a variety, never.
We need not say, therefore, that we dissent from Knight’s theory of natural exhaustion and from every supplement to it put forth since his day. Van Mons’ theory of variation and the tendency of plants to return toward their original type, is to be regarded as nearer the truth.