influence is very injurious to plants in these confined situations: cold raw air, when it comes in contact with the tender foliage of the plants, has the effect of chilling the sap in its progress through their tissue, and thus lessening their excitability, when it should be increased; whilst dry air acts as an incessant drain upon the vegetable juices, which it abstracts through the stomates and pores of the leaves and stems. When cold air is admitted to any position where it can unite with caloric, and not in an equal ratio with moisture, it necessarily becomes arid, and in that state it eagerly combines with moisture in any form with which it can come in contact therewith; and consequently if cold air is admitted to a plant structure, where it can have the means of combining with heat, faster than with moisture, it would be brought into this arid state, and would supply its voracious appetite, by abstracting the juices of the plant. It is a very important question how far this state of things is connected with many of the diseases as they are called, to which plants are subject; for my own part, I believe it to have a very considerable influence in the production of many of them. A shallow bed of soil (k), is all that would be required; for in the winter season, there is nothing gained by encouraging a very luxuriant and gross state of growth: the composition of this soil will be noticed hereafter: beneath it, and resting on the top of the tank, should be placed a layer of coarse open rubble, not less than six inches in thickness; and among this rubble by means of tubes (n), placed at intervals along the bed, I would occasionally pour considerable quantities of water, in order to maintain a due regulation of moisture in, and throughout the soil, among which the vapour arising from the water would ultimately rise. Beneath the tank a space (o), might be provided, which would serve admirably either for the cultivation of Mushrooms, or the forcing of Rhubarb, or Sea Kale. Transverse partitions should be introduced into the bed of soil, so as to divide the roots of each plant from those of its neighbours: this arrangement will admit of a complete succession of plants being maintained, by the removal of those which have become old and debilitated, and the substitution of young and vigorous ones; and this obstruction of the roots, will not be injurious, for the Cucumber does not by any means require to be permitted to extend its roots at random, but will readily submit itself to any rational regimen, with regard to the area from whence it is permitted to extract its food. A portion of soil sufficient to support one or two plants, could by this arrangement be renewed as occasion might require, and the roots of the contiguous plants would suffer no injury from the operation. The pathway of the house, should be paved so as to admit of its being occasionally washed and cleansed.

It will be found to be highly economical in reference to the consumption of fuel, to provide the structure with the means of being covered at night. Shutters of light frame-work, covered with any waterproof material, would be found to answer the purpose admirably; they should be elevated a few inches from the surface of the glass, and they should be arranged so as to confine a body of air, which acting as a very slow conductor of heat, would serve to prevent that incessant drain upon the temperature of the internal atmosphere, which takes place when the material employed is in contact with the glass, as well as when coverings are altogether absent. This would not be the only advantage, for as the covering would to a great extent prevent the radiation of heat from the internal atmosphere, so would it also prevent the necessity of the application of so powerful a degree of fire heat at night; and thus the plants would be permitted to enjoy that natural season of repose so essential to their well being, instead of being forced into growth by reason of a high temperature kept up, solely for the purpose of obviating the external cold.

Chap. III.

ON THE PROPAGATION OF THE CUCUMBER.

Cucumbers are propagated by cuttings, by layers, and by seeds; the two former of these methods being frequently practised by those who have conveniences to keep their plants growing throughout the year; the latter being adopted either through choice or necessity, by the majority of cultivators, or those whose means will not enable them, even if they desired it, to keep up continually a successional growth.

Propagation by cuttings has many advantages to recommend it, especially when viewed in connection with the production of winter fruit. The plants raised by this mode of treatment, in comparison with those raised from seeds, are less gross and succulent in their nature, and more subdued in their manner of growth; whether it may be that having mature and perfectly formed parts, they are enabled to assimilate their food more rapidly, than young and imperfectly formed plants can do; or whether it is owing to any difference in the balance between the roots and leaves, which latter organs, in cuttings, and the former, in seedling plants, may be regarded as predominant, does not appear quite evident, probably the effect depends partly on each of these supposed causes. They are moreover, sooner in arriving at a fruit-bearing state, by reason of a universal natural law, by which the inflorescence and fructification of a plant becomes more general and perfect, in proportion as the plant attains proximity to its perfect developement; which effect, is owing to the more perfect elaboration and preparation of the materials, which when so prepared, furnish the means of perfecting the organs of reproduction. For the same reason, the operation of budding a portion of a seedling fruit tree, on a matured stem, is practised, in order to accelerate its fruitfulness; which result generally follows, in consequence of the difference existing in the nature of the food elaborated by the mature plant, and that deposited by one in an infant state. Thus it is also, that cuttings of flowering plants generally, are far sooner in arriving at a blooming state, than seedling plants of the same species: flowers and fruit being formed only by the aid of the perfectly elaborated sap; which is taken up into the system, and assimilated in the plant, in proportion to the number of healthy and mature leaves, in a full state of action: during the younger stages of growth, the crude material imbibed from the soil, is only partially elaborated, and in this state, is only converted into food suitable and destined to increase the foliaceous organs; but when these latter are in full and vigorous action, a supply of matter, not increased in quantity, but enriched in quality, becomes laid up in the store-house and structure of the plants; and it is by means of this matter, aided by the natural agents, that the nature of the developement is changed from being simply that of the organs of nutrition, to that of the more perfect and important organs of reproduction. Besides the precocity of plants propagated by cuttings, there is also another advantage resulting from the practice, and that is the preservation of particularly desirable varieties; the Cucumber is a plant which readily admits of hybridization, and although the result of this is sometimes to give rise to superior varieties, yet if impregnation is permitted to take place promiscuously, the bad qualities of particular varieties, are as likely to be combined in the succeeding race, as the good and desirable ones: this renders it important that the fruit which are preserved for seed, should have been carefully