The last winter has enabled us to judge more correctly than before of the effects of as low a temperature as we usually experience, even in extreme cases, upon most of the newly introduced trees and shrubs. From information communicated to the Gardeners' Chronicle, and from several other sources, the Horticultural Society have been able to cause an instructive return to be prepared, which is published in the number of their journal just out It is needless to say that this is a subject of the highest interest in the innumerable lovers of "hardy" plants, who spend large soma of money upon their acquisition, and who are greatly annoyed when the assurances that they have received of a costly plant being certainly quite hardy, prove to he fallacious. To be hardy, in the proper sense of the word, a tree must be able to bear not only our ordinary winters, which are remarkable only for their mildness, but those instances of much lower temperature which are certain to oeeurr every ten or fifteen years, and of which we have no previous warning.

The question of hardiness is by no means easy to determine conclusively. Mere identity 01 temperature does not indicate identity of climates; the thermometer may fall to zero in two places, of which one has a warm, dry, well drained soil, the other a cold, damp, heavy soil, and plants will escape in the first which perish in the last A great variety of analogous circumstances, unobserved, and perhaps inappreciable, assist in complicating the matter, so that, for absolute exactness, each species of tree would require to be made the subject of a dissertation. But life is too short for us to wait for elaborate inquiries, and we must be satisfied with such an approximation to truth as can be readily obtained. The most satisfactory way of arriving at such truth is by obtaining returns from many different places, in different situations, and comparing the . evidence relating to each new species with that collected in the same places concerning well-known plants now familiar in all gardens. To say that a species will bear an ordinary winter is too vague an assertion to be useful. To say that it is as hardy as an evergreen Oak or a Sweet Bay, or a common Laurel, is intelligible to every one.

The memoranda published by the Horticultural Society furnish data for such a comparison, which every reader can make for himself, Our limited space only enables us to give the result of the inquiry as regards a few of the more interesting cases.

Among the true Pines it may be regarded as certain that in all places, except the warm south and South-western districts, the following are too tender to be worth planting, viz: Devoniana, Grenvilloe, filifolia, leiophylla, apulcensis, Hartwegi, patula, Teocote, Ruuelliana, canariensis, Mat-toniana, Winccsteriana, Gordoniana, halt pen six, ninensis, Orixabce, occidentals, and pseudo-strobut. On the other hand, the hardy constitution of the following seems to be established, viz: Llaveana, Gerardiana, tuberculata, paluttris, radiata, macrocarpa, Benlhamiana, Lindleyana, Fremontiana, muricata, Montezuma, Ayacahuite, cembroides, otteotperma, Pence, pertica, and Brutia. With regard to -P. inaignis the evidence is conflicting; there is a circumstance, indeed, within our own knowledge which is inexplicable; in the garden of the Horticultural Society were two good sized specimens, one rather younger than the other; the former sheltered partially by a wall, the latter as much or more sheltered by a conservatory; the younger died, the older sustained no injury: bo again at Congleton, some are returned killed, others as having escaped; at Ossington, where the Sweet Bays perished, this plant was uninjured, and it is returned by Mr. Lowe, of Nottingham, where the frost was more intense than elsewhere, as being merely "injured." We incline to regard the plant as hardy after it is eight or nine years old.

Of Spruces the following seem hardy, viz: Abies Stnithiana, Morinda, orienialu, and all the.

Among Silvers and their allies Abies Pinsapo, Webbiana, jexoensis, cephalonica, Nordmanniana, and Pichta are hardy; on the contrary, A. religiosa will not stand.

All Larches except Griffithi seem to be hardy.

The Cedar of Lebanon represents sufficiently the constitution of other Cedars; the reports respecting the Deodar are much the same; in both cases plants have died, or suffered, or escaped. Practically we may regard the Deodar when old and well established, quite as hardy as the Cedar of Lebanon; when young it grows so fast as to be more susceptible of very severe spring frosts. Thus when the thermometer fell to 18°, on the 24th of last April, the young Deodars were in full growth in Mr. Glendinnixg's nursery, at Turnham Green, and nearly all perished. the young wood of the common Walnut was killed at the same time.

Among Cypresses, Cupressus funebrie appears to be unsuited to Nottinghamshire and the counties to the North, probably because it has not summer heat enough; the same may be inferred of C. Uhd'ana, Goveniana, torulosa and thurifora; O. maerocarpa appears to be more hardy, fur no plant was quite killed even at Ossington, and at Oulton it sustained little injury. On the other hand it is returned by Sir Oswald Mosley among his killed. We have some hope that all these Cypresses will become hardier as the specimens acquire age; while young they grow so fast and so late as to be peculiarly susceptible of cold.

The returns relating to Junipers show how little they are cultivated. It, however, appears certain that J. excelsa, eguamata, recurva, chinesis, japonica, and inexicana are hardy; and Bermu-diana, tetragona, and Bedfordiana unmistakably tender.

Among other Coniferous plants, Araucaria imbricata has suffered far more than was expected, and evidently will not bear the climate of Derbyshire, and the bordering counties; this is a very unexpected result; it seems also to be ascertained that in a climate that suits it, it will bear well exposure to the sea, a quality of which those who live on the coast, where there is no chalk, will do well to avail themselves. The other Araucarias are not worth further trial All species of Callitris are tender. All the Cephalotaxi are as hardy as Yews; a great discovery, considering how handsome those evergreens. are. Cryptomerias, when in health, suffer nothing; even the fine variety Lobbi, obtained from the Dutch Botanic Garden at Buitenzorg in Java, was untouch* ed so far north as Cheshire; but unhealthy specimens were turned brown in many places. Concerning Cunninghamia we have no northern evidence; up to the latitude of London it may be regarded as about as hardy as a Sweet Bay or Magnolia grandiflora.

Dacrydiums, Phylloclades and Dammars are not worth further triaL Of Fitzroya we have the following account: "Not injured, Chitwick; cut back to the main stem, but recovering, Aeton Green; not affected during the winter, Bagshot; stood well, not being injured in the least, Ware; leader killed down - supposed to be hardy, Alton; unhurt, Rolletton; escaped with slight injury, Congleton; not hurt, Exeter; uninjured, Singleton; under south-east wall, leader killed about 5 or 6 inches, Southampton; slightly protected, uninjured, Bicton;" we therefore regard it as hardy, the injury it sustained being probably caused by the youth and rapid growth of the specimens. Glyptostrobus is hardy. Libocedru* chilensie is an unanticipated addition to hardy Conifers; it seems to be undoubtedly as hardy as a Chinese Arbor Vitae. Concerning the Podocarps all remains uncertain; they are worth further trial. Retinisporas seem to be tender. Of Saxo-Gotbsea the reports are contradictory; the following is the return concerning it: - "Is scarcely alive, but not quite killed, although hopeless, Chietoick; cut back to the main stem, but recovering, Aeton Green; not affected during the winter, Bagehot; stood well, not being injured in the least, Ware; perfectly hardy, Alton; unhnrt, Rolleston; escaped with slight injury, Congleton; not hurt, Exiter; uninjured.

Singleton; promises to prove as hardy as any of the Yews, Bicton." We hope the Bioton judgment will be confirmed; we know that the plant which died at Chiswick was out of health; and that the specimen at Acton Green, although it had grown very fast and failed to ripen its wood, exhibited no sign of suffering till the thermometer fell to 4°, and was succeeded by a bright morning sun. Taxodhtm sempervirers must receive a verdict of hardy, although its leaves and young shoots were nipped and turned brown; the common Yew was as much hurt in some places, especially plants transplanted in the previous autumn. Thujas, all hardy. About Torreya nuei/era there is but one return, from Hampshire, and that is favorable. - Gard Chron.