certainly protected the sap-vessels from the cold. This withering of the leaves of transplanted trees, by which large transplanted trees so {268} frequently perish, is most prevalent in cold damp soils, when the air is dry and the sun powerful, and evidently results from the superior vegetation being in advance of the inferior; torpor of the roots, not torpor of the sap-vessels of the stem from cold. It is also perfectly evident, that trees with long naked stems will suffer most, as their leaves are raised higher, more in the current of the drying wind; their root and top farther asunder, therefore less liable to contemporaneous impulse; the sap-vessels of the stem longer and more attenuated, therefore the streams of fluids from the soil, not only smaller, but also more liable to obstruction, or to flow slowly, from the insufficiency of the vital impulse, or of endosmose in the wounded sickly plant to impel to such a height. Our author’s assertion, that the rough epidermis generally covering the live bark of trees in open situations, is necessary to the health of the tree, in protecting the sap-vessels from cold, is, we think, not quite correct. Some time ago we caused the dead epidermis be hewn down from several trees, in a rather exposed situation. This was done with considerable nicety, and extending up along the branches. We remember of one case, of very thick indurated epidermis, where a carpenter was employed more than a day in laying bare the live bark of one tree. {269} Instead of suffering injury by this exposure of the sap-vessels to cold, the trees rather acquired new vigour from the operation; and the particular tree alluded to, was unusually luxuriant the season following this flaying, which was performed in winter. Now, to apply Sir Henry’s analogy of fur of animals, would an arctic fox have been benefited by exposure to the winter’s cold in like plight? We also think Sir Henry will find the trees of dry climates have a much thicker coating of dead bark than in cold countries, evidently a consequence of desiccation[51], and, if Sir Henry must have animal analogy—similar to the desiccation and cracking of the skin of man in arid air. {270} It is a subject of considerable difficulty to explain the cause of slender lengthened shoots in sheltered situations, and short stout shoots in exposed. Sir Henry solves this “excellently well” in two ways, first, attributing it to shelter and exposure themselves,—“for shelter is heat, and exposure cold,”—and again, to an instinctive straining in the sheltered to reach the light, of which its neighbours deprive it every way but from above, and would do so there too if it failed to exert itself.