The great stimulants of vegetable life are heat, air, light, and moisture, and in the management of cuttings those agents must be regulated with care and precision; the kind and degree of care will vary according to the nature, age, and condition of the cuttings under consideration. Every one who has had experience in this mode of propagation is aware that, under certain conditions, cuttings will grow and put forth leaves without forming roots; while, under different circumstances, the same kind of cuttings will produce roots without indicating the slightest symptoms of growth by the buds. Heat is the active stimulant of the vital forces of plants, and when the atmosphere by which they are surrounded is of a comparatively higher temperature than the soil in which they are inserted, the branches are excited before the roots. On the other hand, when the soil is warmer than the air, the root-forming process will be active, although the branches show no indication of growth. Of course neither of these conditions can long continue, for without a reciprocal action the plant will speedily die; the effects of these conditions are frequently illustrated in our pleasure grounds and orchards with spring-planted tree6. Toward the latter part of spring and the early portion of summer, the air is many degrees warmer than the soil.

The atmospheric heat excites the buds, and leaves are developed, but the recently disturbed roots in the colder soil have-not yet been excited, and are not in a state to supply the demands of the foliage. The juices of the tree are soon exhausted, and the promised healthy growth is suddenly and hopelessly checked.

The main point of consideration, therefore, in the growth of cuttings, is to stimulate into activity the processes carried on in the vessels beneath the soil, while the upward growth is retarded. This is secured by heating the soil. Heating the air will stimulate the buds and injure the cutting. The cuttings should be kept in an atmospherical temperature as low as the nature of the plant will allow, and by applying heat to the soil, to raise its temperature as high as the roots of the plants will endure. The more completely these conditions are maintained, the greater certainty there is of success, and with ordinary care in the future management, failures cannot occur.

(To be continued).