Perhaps there is no point whatever, connected with Horticulture, of greater interest than that which forms the subject of this paper; it is the distant goal towards which we all are striving, but of which, alas! we have not as yet even caught a glimpse. The gardener is in possession of the powers by which he can bend the seasons to his will; he can dispel the frozen gloom of winter with the rich warm glow of the vintage; at his call the flowers of spring and summer start up beneath his feet, and his hothouses are filled with the luscious fruits of the torrid zone. All this he knows how to effect with an artificial climate; but he has no influence over the natural climate of his country, nor can he impart to the vegetation of warmer latitudes the least additional power of resisting cold, for which they have not been prepared by nature. Acclimatizing is still a secret to be discovered. To [p165] this day not a single instance can be adduced of any exotic plant whatever possessing greater powers of withstanding cold, than it had when first introduced. It has been hoped that if the seeds of given plant could be procured, for many generations, in a climate severer than its own, the offspring so obtained would gradually accommodate themselves to their new country; but no such result has followed from the experiments that have been tried. Let us take a few familiar examples:—the common nasturtium, (Tropælum majus,) a native of Peru, is said to have been introduced about the year 1686. At the time at which we are writing, it must have descended through about 140 generations; and yet it has not become in the smallest degree capable of resisting cold. Of the mignonette (Reseda odorata), the date of introduction is not well ascertained; it has probably been a favourite border annual for sixty or seventy years, and yet it has in no degree shaken off its annual character, which is unnatural to it, and resumed the suffrutescent habit which it possesses in its own milder climate. The potato, too, which has for two centuries and a half been increased in every conceivable manner, by seeds as well as by offsets, bears cold in no degree more readily than it did in the sixteenth century. Nor does it appear to us probable, that acclimatizing, if practicable, is to be brought about by sowing seeds in northern latitudes through successive generations. We do not believe that plants will bear their seeds at all in a temperature much lower than that in which they have been located by the hand of Nature. The heat of a northern summer sufficiently approximates to that of the tropics, to be considered, with reference to vegetation, as the same, and it is during that season that the seeds of all plants are ripened; the conditions, therefore, under which the seeds of Tropæolum, for example, are produced in England, do not materially differ from those under which the same seeds are produced in Peru; if the season proves unpropitious in any considerable degree, they are not produced at all. How then can it be expected that seeds ripened under similar circumstances, but in different latitudes, should give birth to a progeny differing in any remarkable particular from their parents? In fact, in power of resisting cold, they do not differ at all. If such a capability were to obtained, it would be by inducing plants to ripen their seeds in winter.

But if it is certain that nothing is to be gained in acclimatizing, by raising plants from seed through successive generations, [p166] it is no less true that many trees, which have been supposed to be incapable of surviving a northern winter, are now ascertained to be perfectly hardy, and that the power of enduring cold may be increased in others, by a judicious management of soil and situation.

The phenomenon of vegetable life being destroyed by cold, probably arises from the vessels, through which the circulation and secretion of the fluids of plants take place, being ruptured by the expansion, from cold, of the fluid they contain. In proportion, therefore, to the tenuity of the vessels, and the abundance of their fluid, will be the danger to which they are exposed from frost; and to the strength of the vessels, and the paucity of their fluid, the power of resisting cold. Thus vigorous shoots of the oak, walnut, and many other trees, which are formed with rapidity, imperfectly matured, and highly charged with fluid, are extremely impatient of cold, and are even destroyed by a few degrees of frost; while the twigs and branches of the same trees, which are formed slowly, fully matured, and incompletely filled with fluid, bear unharmed the utmost rigour of our winters. In acclimatizing, therefore, this law should be carefully remembered, and the situations in which tender plants are stationed, should be those in which their growth is restrained, and an excessive absorption of fluid prevented.

This appears to have been the true secret of the success that has attended the attempts at acclimatizing, which form the subject of Mr. Street’s communication. By planting in situations well drained from superfluous moisture, under circumstances where rapid growth was rendered impracticable, and, as we understand, in a garden admirably adapted to the object, from its position, he has succeeded in naturalizing, in latitude 56° N., plants which have not yet been known to endure the winters even of the parallel of London.

V. Upon the Culture of Celery. By Thomas Andrew Knight, Esq., F.R.S., President. [◊]

“That which can be very easily done, without the exertion of much skill or ingenuity, is,” Mr. Knight observes, “very rarely found to be well done, the excitement to excellence being in such cases necessarily very feeble.” This remark is in the present case applied to the cultivation of celery, which, being a native of the sides of wet ditches, might naturally be expected to demand an abundant supply of water when cultivated. Accordingly, Mr. Knight found that by keeping the ground, in which celery was planted, [p167] constantly wet, it grew by the middle of September to the height of five feet, and its quality was in proportion to its size. Mr. Knight also recommends planting at greater distances than is usually the case, and covering the beds, into which the young seedlings are first removed, with half-rotten dung, overspread to the depth of about two inches with mould; under which circumstances, whenever the plants are removed, the dung will adhere tenaciously to their roots, and it will not be necessary to deprive the plants of any part of their leaves.

VI. Report upon the New or Rare Plants which flowered in the Garden of the Horticultural Society at Chiswick, between March, 1825, and March, 1826. Part 1. Tender Plants. By John Lindley, Esq. [◊]

The subject of this paper consisting of botanical details which do not bear curtailing, we shall only extract the names of the new species described in it, as a guide to our botanical readers. In the whole, thirty-three species are noticed; of which the following are published for the first time:—

VII. Account of a Protecting Frame for Fruit-Trees on Walls. By Mr. John Dick. [◊]