The numerous hybrid varieties which are in cultivation, render it a matter of some importance to make choice of those most suitable to the purpose; these are however so continually changing, that it is useless to attempt a record of them. The Sion house Cucumber is perhaps the best of all suited for cultivation in the winter season. The principal features which are required in Cucumbers for winter forcing, are, precocity; compactness of growth, rather than luxuriance; prolificacy, rather than extreme length of fruit; and hardiness of constitution: these, are to the gardener far more important points, than those which entitle them to rank as "prize" varieties. CHAP. IV. ON THE TREATMENT OF THE MATURE PLANTS. From the time that the plants become established, which is the period of their existence now about to be considered, they require to have the elements of vegetable growth duly supplied to them, in order to secure their successful developement. It is not enough to plant them in proper soil, and duly to water them, unless attention is also paid to the temperature, as well as the constituents of the atmosphere to which they are submitted; neither will attention to these latter points be sufficient to ensure success, if at the same time, the former are neglected. A _soil_ of suitable chemical, as well as mechanical composition, a pure and wholesome _atmosphere_, _water_ promptly and properly applied, and _heat_ duly regulated, are conditions which equally require minute care and attention in their adaptation; and these being applied upon the comprehensive, and perfectly harmonious principles of nature, will leave but little to be done in the shape of expedients, which are too frequently resorted to, as the means of counterbalancing either defective or unsuitable management. The application of these agents to the cultivation of the plant under consideration, in the winter season, will form the subjects of succeeding chapters. I will here briefly direct attention to the importance of light in the growth of plants, and then devote some space to the consideration of the subject of pruning and training.