Light is most essential to the perfect and healthy developement of vegetable organization, the performance of the functions essential to the health of plants being dependent on its agency. It cannot indeed be assumed that plants will not continue to grow, unless they are supplied with an intense degree of light; but it is certain that the successful nature of their growth, their maturation, and their fructification, are dependent in no ordinary degree upon the nature and force of its action; for without it, the vital energies of animated beings are unable to maintain and perform the processes of elaboration, and assimilation, upon which their nutrition depends. The mere extension of vegetable tissue, may indeed go on, though less satisfactorily, under the almost total privation of light, but with the exception of cryptogamic vegetation, the organs of fructification are not under those circumstances, produced at all: the stem may be formed, but does not become solid: the leaves may expand, but their condition is imperfect; and it is only by means of the full and complete action of these organs in the nutrition of plants, that the developement of the floral parts is brought about: the roots may take up fluids, and these may be conveyed in the natural upward channels, and then dispersed among the stems and the leaves; but it is the action of solar light, aided indeed by the natural condition of the elements supplying heat and moisture, which alone, by a process of elaboration, can convert this fluid, once crude and undigested, into the compound organic substances, such as lignin, gum, starch, gluten, &c. which in their turn, are destined to minister to the support of the organs of reproduction. Growth, that is mere extension, may go on in proportion as heat and moisture are supplied to plants, but light is the agent to whose especial influence we owe the production of their active properties and secretions, and the perfection of their fruit.
If then light is so indispensable to the vegetable frame, how important it is that the structures which we devote to the cultivation of such plants as the Cucumber, which are naturally habituated to an eastern clime, should be so designed, as to offer the least possible obstruction to its entrance: how important, too, that the glass we employ, which in its purest state, offers considerable obstruction, by refracting the rays of light, should be as transparent and untarnished as possible, so as to admit them as perfectly as can be practicable; instead of which, it is too often disfigured by an accumulation and deposit of filth, which, to say the least, must materially diminish their force: how important, moreover, that whatever coverings it may be necessary to employ during the night to prevent the outward radiation of heat, should be speedily removed in the morning, and kept off as long as they safely may be, in order to permit the inward radiation of light. When these matters are all duly attended to, our climate, at least during the winter, still offers obstruction enough to our success, in its mists, and fogs, its long dark nights, and dismal cloudy days, and therefore wisdom would teach us, to avail ourselves of all which we can grasp, by a course of untiring assiduity, and attention to such apparently trifling matters as these.