The beauty of one species of Hoya, viz., H. _carnosa_, has long caused it to be a favourite with collectors. The object of the writer of this paper is to call attention to such others as are known to exist in gardens, or as are preserved in the records of the botanist. The following species form the subject of the paper, viz.: 1 Hoya carnosa, _R. Brown_. 2 Hoya crassifolia, _Haworth_. 3 Hoya pallida, _Lindley_. 4 Hoya Pottsii, (Tab. I.) 5 Hoya trinervis. These five are all the species at present cultivated in gardens; others are known to exist in the warmer regions of Asia, where they should be assiduously sought for by travellers, as they are not only very ornamental, but easily to be transported to Europe. From such materials as he has been able to procure, the writer enumerates the following as completing the genus Hoya, as far as at present ascertained: 6 Hoya chinensis. 7 Hoya viridiflora, _R. Brown_. 8 Hoya lanceolata, _D. Don_. 9 Hoya linearis, _D. Don_. 10 Hoya australis, _R. Brown_, _MSS_. 11 Hoya nicobarica, _R. Brown, MSS_. 12 Hoya augustifolia. The paper concludes with a detailed explanation of the best manner of cultivating Hoyas. IV. _On acclimatizing Plants at Biel, in East Lothian_. By Mr. John Street, gardener to the Honourable Mrs. Hamilton Nesbitt. 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