in the soil, and that their roots are the mouths through which the food is conveyed into their body. But the absorption of fluid does not take place either by all the surface of their roots, nor even of their fibres, but only by the extremities of the latter, consisting of bundles of vessels surrounded by cellular tissue in a very lax spongy state, whence those extremities are called spongioles. That it is only through the spongioles that absorption to any amount takes place, is easily shown by growing a plant in water and alternately preventing the action of the spongioles, when languor and a cessation of vital action comes on, and preventing the action of the general surface of the roots, leaving the spongioles at liberty, when the vital energies are immediately renewed. These spongioles are exceedingly delicate in their organisation, and a very slight degree of violence destroys them. It is scarcely possible to remove the soil from the roots without injuring them in some degree and if transplantation is effected violently or carelessly, they are in a great measure destroyed. In proportion to the size or age of a tree, is the difficulty of preserving them increased; and hence at the same time the difficulty of transplantation is augmented. If, by any method, the spongioles could be preserved unharmed, there would be no reason whatever why the largest forest tree should not be removed as easily as the young plants in a nursery; but their preservation in such cases is impossible, and therefore the transplantation of trees of great magnitude cannot be effected. It is because of the security of the spongioles from injury when the earth is undisturbed, that plants reared in pots are transplanted with so much more success than if taken immediately from the soil. Hence, also, when earth is frozen into a huge ball around the root of a plant, transplantation is effected with the same kind of certainty. The practice of cutting the roots of large trees the year previous to removing

them is attended with success for a similar reason. Wherever the roots are cut through, the new fibres which are emitted, provided a plant is in health, in short tufts, and each terminated by a spongiole, are much more easily taken out of the ground without injury than if they were longer and more scattered among the soil. When destroyed, the spongioles are often speedily replaced, particularly in orchard trees, provided a slight degree of growth continues to be maintained. This is one of the reasons why trees removed in October succeed better than if transplanted at any other time. The growth of a tree at that season is not quite over; and the first impulse of nature, when the tree finds itself in a new situation, is to create new mouths by which to feed when the season for growing again returns.

Evaporation takes place in plants to an inconceivable degree in certain circumstances. It is known by the experiments of Dr. Hales, that a sunflower plant will lose as much as 1lb. 14oz. by perspiration in twelve hours; and that in general," in equal surfaces and equal times, a man would perspire 5, the plant 15, or as 50: 15;" and that taking all things into account, a sunflower perspires 17 times more than a man. The same most accurate observer found that a cabbage perspired in twelve hours 1 lb. 9oz.; a Paradise Stock in a pot, 11 ounces; and a Lemon Plant, 8 oz. Guettard states that he found Cornus Mascula perspire twice its own weight in a day; and Mr. Knight has remarked a Vine in a hot day losing moisture with such rapidity that a glass placed under one of its leaves was speedily covered with dew, and in half an hour the perspiration was running off the glass. In damp or wet weather this evaporation is least; in hot dry weather it is greatest. This loss has all to be supplied by the moisture introduced into the system by the spongioles; and hence, if the spongioles are destroyed, and evaporation

takes place before they can be replaced, a plant must necessarily die. This is the reason why deciduous trees cannot be transplanted when in leaf; it is impossible to remove them without injuring their spongioles, and it is equally impossible to hinder the evaporation by their leaves: but if they are kept in pots, it matters not at what season their removal takes place, because as their spongioles are then uninjured, even excessive evaporation would be made good by their action. It is well known that certain evergreens, such as Hollies, Laurels, &c. can be transplanted in almost all months; this arises from their perspiration being much less copious than in deciduous trees, wherefore the spongioles have less difficulty in supplying the loss occasioned by it; yet even evergreens cannot be removed in the hottest months in the year, because then the action of such spongioles as may be saved in the operation would not be sufficient to supply the waste by evaporation. Plants first beginning to grow in the spring, with their leaves just turning green, are in a most unfit state to remove; for, when transplanted, their roots will not have time to form a sufficient number of new spongioles to supply the loss to which the rapid perspiration by the leaves at that season will give rise. It is upon this same principle, that if deciduous plants are taken from the ground in the summer, they are put into pots and placed in a hot-bed to recover; not for the sake of the heat, but because the atmosphere of a hot-bed is so charged with humidity that perspiration cannot go on, so that the vital energies of the plant, instead of being wasted by evaporation, are directed to the formation of new mouths by which to feed.

This is but a brief outline of what the principles are upon which the common operations of the Fruit Garden depend; yet it is hoped that it may not be without its use in calling attention to the rationalia of

what may seem extremely simple and well-understood practices, but which are undoubtedly neither so perfect, nor generally so skilfully performed, as to be incapable of amendment.

xxix

ABBREVIATIONS, AND BOOKS QUOTED.

Aiton's Epitome. Epitome of the 2d Edition of the Hortus Kewensis. By W. T. Aiton. 8vo. London, 1814.

Baumann's Cat. Catalogue des Végétaux en tout Genre disponibles. dans l'Etablissement des Frères Baumann, à Bolwiller. 1826.

Bon Jard.

Le Bon Jardinier. Par A. Poiteau, &c. Bradley. New Improvements of Planting and Gardening. By Richard Bradley. 1724.

Chaptal's Tr. sur la Vigne. Traité Théorétique et Pratique sur la Culture de la Vigne, avec l'Art de faire le Vin, &c. Par MM. Chaptal, Rozier, Parmentier, et Dussieux. 2 vols. 8vo. 1801.

Coxe's View. A View of the Cultivation of Fruit Trees, and the Management of Orchards and Cider, &c. By William Coxe, Esq. 8vo. 1817.

Diel's Pom.

Diel's Versuch.

{

Versuch einer Systematischen Beschreibung

in Deutschland vorhandener Kernobstsorten. Von Dr. Aug. Friedr. Adr. Diel. 24 vols. small 8vo. 1799-1825.

Duhamel. Traité des Arbres Fruitiers. Par M. Duhamel du

Monceau. 2 vols. 4to. Paris, 1768.

Forsyth. A Treatise on the Culture and Management of Fruit Trees. By William Forsyth. 8vo.

Hanbury. A Complete Body of Planting and Gardening. By the Rev. Wm. Hanbury. 2 vols. fol. 1770.

Hitt. A Treatise on Fruit Trees.

Edition. 8vo. 1768.

By Thomas Hitt. Third

Hooker's Pom. Lond. Pomona Londinensis. By William Hooker. 4to. London, 1813.

Hort. Gard. Coll. A Collection of Fruit Trees in the Garden of the Horticultural Society at Chiswick.

Hort. Soc. Cat. A Catalogue of Fruits cultivated in the Garden of the Horticultural Society of London. 8vo. 1826. Hort. Trans. Transactions of the Horticultural Society of London. 4to. 7 vols.