These may be considered separately: 1st--It may be assumed, and has been already well established by botanists, that every plant has its own peculiar constitution, adapting it to certain atmospheric conditions, and that for its healthful and successful culture, these must be understood and adhered to, within comparatively narrow limits. Tropical plants, as is well known, cannot be cultivated beyond their natural limits, except under circumstances where their natural conditions are nearly imitated by the gardener; and even in our stoves and hot-houses, these plants do not compare in vigor with their fellows that luxuriate in the hot and steaming atmosphere of the tropics, under the stronger light of such a clime as is natural to them. On the contrary, the plants of northern latitudes will not grow and produce seeds where temperature is too elevated. Those from a humid atmosphere suffer in an arid clime, and those which thrive in dry sandy regions suffer equally when introduced into a humid atmosphere. Thus we find, that where there is too much moisture for some of our cultivated plants, they are inclined to be too succulent, and this very excess may produce a dropsical condition that is really a state of disease. Thus we suffer in a loss of fruit, which will fall badly before its period of maturity, and that which remains its full time is found to be thin and watery, deficient in the high spicy aromatic flavor which is so highly appreciated by the connoisseur of these choice products. When, on the other hand, the arid character of the soil and climate prevail to an extent that is uncongenial to any particular fruit, we shall find that its growth is arrested, and that its highest qualities are not adequately developed: this is frequently observed in an unusually dry season--and in California, where irrigation is required to enable the orchardist to produce some of the succulent fruits, the most remarkable size and beauty have been attained, but we are told that it was often at the expense of the desired flavor that the same varieties acquire, under circumstances more advantageous to the development of their superior qualities. So in many of our fruits, the successful results depend upon the hygrometric condition of the atmosphere, and Liebig suggests that a very prolific source of diseased action in plants, arises from the suppressed evaporation and transpiration consequent upon such atmospheric conditions.