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ted, others obtained from apple trees which grew from cuttings, and others from the seed of each kind of fruit afterwards inserted on them; I was surprised to find that many of these stocks inherited all the diseases of the parent trees.”—Mr. Knight came at last to the conclusion, which subsequent experience has fully confirmed, “that all efforts, to make grafts from old and worn out trees grow, are ineffectual,” and that “the durability of the apple and pear may be different in different varieties, but that none of either would vegetate with vigor much, if at all, beyond the life of the parent stock. I am confirmed in this opinion by the books on this subject; of the apples mentioned and described by Parkinson, the names only remain, and those since applied to other kinds now also worn out; but many of Evelyn's still remain (1795), particularly the red streak.

This apple, he informs us, was raised from seed by Lord Scudamore in the beginning of the last century. We have many trees of it, but they appear to have been in a state of decay during the last forty years - - - - - - the durability of the pear is probably something more than double that of the apple.” Many of the readers of this paragraph will probably recall to mind the gradual and complete extinction of the unrivaled “Golden Pippin,” which has evidently afforded a proof of the truth of Mr. Knight's deductions. His experiments on seedling apples, while the excellence of several of the sorts affords much encouragement to gardeners and landed proprietors to imitate his example, and endeavor to replace by new fruit trees of equal goodness, the kinds whose limit of duration may be pretty nearly guessed, also show the necessity in this, as in most pursuits, of the valuable qualities of patience and perseverance which he must himself have possessed in so great a degree, since of the seeds he sowed he reckoned that one in a thousand came up which was not a crab, and one in a thousand of these became a good eating apple.

78. There is one more subject, connected with reproduction by seed, which is too curious to be passed over ; the wonderful tenacity of vegetable life. This, indeed, is shown in the plants themselves in many instances, such as the enormous longevity of some trees, particularly the oak, the yew, and some of foreign growth,” but it seems even more extraordinary as it exists in seeds. The latter will remain torpid for many months or even years without injury. Corn grains enclosed in the bandages which envelop the mummies, are said to have occasionally germinated, though most of them seem to have lost their vitality. There is nothing improbable in the fact ; but as the Arabs, from whom the mummies are commonly obtained, are in the habit of previously unrolling them in search of coins, &c., it is not always certain that the seeds which have sprouted, were really at first enclosed with the mummies.t

* In the Appendix will be found translated a table given by De Candolle of the presumed age of some celebrated trees. (B.)

t Carpenter’s Veg. Physiol., § 451.

CHAPTER W.

COMPARISON OF VEGETABLE WITH ANIMAL PHYSIOLOGY.

79. It is impossible to consider the subject of Vegetable Physiology and organization, without being struck by the analogy which it presents in so many points to that of Animals.-Yet, however strong may be that analogy, it never in any instance becomes identity, and the marked fact, noticed in the Introduction, that the latter in all cases convey their food by the mouth to a stomach, is alone sufficient to establish a boundary between them;" the comparison, however, between the two, is so interesting and instructive, that a few words may be well bestowed upon the subject.

The whole range of functions both of animals and plants, that is to say as far as nutrition and reproduction are concerned, affords ample illustrations of the near approach to similarity in the two kingdoms —a few examples of each may prove the truth of

* There does indeed appear to be one group, about which some doubt exists in the mind of some physiologists as to its reference to the animal or vegetable kingdom. “ They are mostly,” says Dr. Carpenter, “formed of cells jointed together, as the Conferva, ; but some of them seem to possess a different interior structure; and others exhibit very curious motions, which can scarcely be distinguished with certainty from those of animals.” (Carpenter's Weg. Phy., p. 44.)

this assertion, while the difference will also in general be equally perceptible. In the entire course of that function by which the individual is nourished, the main point holds good in both cases; i. e., that matter fitted for its food is taken into the system by the appointed organs, thence conveyed through the necessary channels, assimilated and converted into the requisite substance for continuing and replenishing the tissue of the body, and furnishing the needful secretions, while such as is unavailing to any of these purposes, is excreted. In the plant, however, the juices are not conveyed to a single receptacle, there to be elaborated, but, according to the process detailed in the foregoing pages, are gradually in their progress converted from the crude into the nutritive sap. The circulation of this sap, and the power of the glands to convert it into peculiar secretions, suggests immediately to the mind the idea of an analogy with the circulation of the blood in animals, and a fanciful imagination might see a degree of further likeness to the venous and arterial blood in the two states of the sap. The similarity, however, though it does exist, is but very partial, no one general circuit of the sap throughout the system, as there is of the blood originally propelled from the heart, really taking place. Again the tissue produced and nourished in the two kingdoms, though very analogous in some respects, is by no means identical:—the cellular teature of animals differing from the cellular tissue of plants by its structure, which is not actually composed of individual cells, united together by the cohesion of their walls, but of “a congeries of extremely thin laminae or plates, variously connected together by fibres, and by other plates, which cross them in different directions, leaving cavities or cells.”* This cellular texture, however, forms the essential material of the animal fabric generally, as the cellular tissue does of the vegetable. The important chemical difference between animal and vegetable organized tissue has already been noticed, viz., the presence of nitrogen in the one case and its absence in the other (45). - .

80. Perhaps, however, the most curious and interesting analogy between animal and vegetable organization is that which relates to the process of reproduction—which in some of the lowest tribes of animals approaches more nearly to identity with that of plants than in any other function. In several of the most minute of the Infusoria, in which nevertheless, small as they are, the patient investigation of Ehrenberg has discovered a series of stomachs, we meet with frequent examples of multiplication by the spontaneous division of the body of the parent into two or more parts. “Many species of Monads, for instance, which are naturally of a globular shape, exhibit at a certain period of their development a slight circular groove round the middle of their bodies, which by degrees becoming deeper, changes their form to that of an hour-glass; and the middle part becoming still more contracted, they present the appearance of two balls united by a mere point. The monads in this state are seen swimming irregularly in the fluid; as if animated by two different volitions; and apparently for the purpose of tearing asunder the last connecting fibres, darting through the thickest of the crowd of surrounding animalcules; and the moment this slender ligament is broken, each is seen moving away from

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