Acclimatization is rendering a plant capable of the production desired in a climate differing from that in which it is native. In our climate it is usually required to induce a plant to endure lower temperatures than those to which it has been accustomed, and this, though some are intractable, is more easy than is inducing the natives of colder regions to live in our latitudes. When a new plant arrives from a tropical country, it is desirable to use every precaution to avoid its loss, but so soon as it has been propagated from, and the danger of such loss is removed, from that moment ought experiments to commence, to ascertain whether its acclimatization is attainable. That this should be done is self-evident; for the nearer such a desirable point can be attained, the cheaper will be its cultivation, and consequently the greater will be the number of those who will be able to derive pleasure from its growth. Hence it is very desirable that an extended series of experiments should be instituted, to ascertain decisively whether many of our present green-house plants would not endure exposure to our winters, if but slightly or not at all protected.

It may be laid down as a rule, that all Japan plants will do so in the southern states, but it remains unascertained to what degree of northern latitude this general power of endurance extends. Experiment, and experiment only, ought to be relied upon; for we know that the larch was once kept in a greenhouse in England. Many tropical plants of every order and species, have been found to require much less heat, both during the day and during the night, than gardeners of a previous century believed. Other plants than those already noticed have passed from the tropics to our parterres, and even to those of higher northern latitudes. The horse chestnut is a native of the tropics, but it endures uninjured the stern climate of Sweden. Aucuba Japonica and Paeonia Moutan, we all remember to have passed from our stoves to the green-house, and now they are in our open gardens. Every year renders us acquainted with instances of" plants being acclimatized: and, in addition to those already noticed, we find that Mr. Buchan, Lord Bagot's gardener, at Blithfield House, in Staffordshire,, has an old cinnamon tree (Laurus Cinnamo-mum) under his care, which ripens seed: from these many plants have been raised that endure the winters of England in a conservatory without any artificial heat.

Then, again, there is no doubt that all the conifers; of Mexico, which flourish there at an elevation of more than S000 feet above the sea's level, will survive our winters in the open air. Among these are Pinus Llaveana, P. Teocate, P. patula, P. Hartwegii, Cupressus thvri-fera, Juniperus flaccida, Abies religiosa, and some others. Many natives of the southern states have been gradually acclimated in Pennsylvania; experience has, however, demonstrated that the nature of the soil is all-important. On sandy or light loamy land with gravelly subsoil, many plants are found to withstand the winter, which would surely perish on heavy or wet land. So also the aspect as regards exposure to the sun, it having been found from repeated observation that tender plants, especially if evergreen, suffer less from cold when screened from the sun's rays. The cause is obvious. An extensive importation of European Holly received at the Landreth Nurseries, were, as a protection from the summer sun, planted on the north side of a high board fence, where they safely resisted the seventy of winter: subsequently they were placed in open positions, and all were killed by the combined action of heat and cold.

The following general rules are the results of experiments in the London Horticultural Society's Garden, conducted by Mr. Gordon. 1. "Plants intended to be acclimatized, should never be subjected to artificial heat during the winter that precedes their being planted out; if obtained from seeds, as little heat as possible should be employed in raising them; and starved or stunted plants are more likely to succeed than such as have been forced into a rapid and luxuriant growth. 2. The plants should not be committed to the open ground earlier than the end of May; the soil should be poor, dry, and thoroughly drained; if against a wall, the border should be protected through the entire winter by a roof of hurdles thatched with straw, and projecting about three feet".