General Notices. 387 



of periderma is so situated, that a part of the bark substance is completely 

 separated by it, which tlien slowly dries, and, after gradual disunion, actually 

 falls off. These new formations of new layers of periderma are repeated, and 

 thus follows the continual dilamination, by which the tree still retains a very 

 even bark. The great scales of bark, which fall off, consist, however, of the 

 cellular envelope, and of a portion of the substance of the liber. The scales 

 of the bark in Primus, Pyrus, C'ratae^gus, Quercus i?6bur, niia europae^a, &c., 

 are said to originate in the same manner as in the plane tree. Mohl, with 

 other botanists, distinguishes these thick inner layers of the bark of the cork, 

 which are formed in quite a different manner, and calls the inner layer 

 the rugose bark (rhytidoma, from r//i/tis, a wrinkle). The results of these 

 observations are, that the origin of the scales of the surface of the bark 

 of dicotyledonous plants is not to be sought for in a desiccation of the bark 

 layers, and in a mechanical splitting of them ; but that it depends on the later 

 developement of distinct cellular layers, which disunite the single bark scales, 

 or prepare for their disunion, or even themselves form the scales. Upon the 

 whole, we may suppose two main differences in the later developement of the 

 cellular tissue of the bark. In the first case, the layers ai'e developed outside 

 the cellular envelope ; and in the other, the becoming thicker arises from the 

 developement of a stratum of cells under the cellular layer. In the first case, 

 it is generally cork substance which is formed ; in the second, rough bark 

 (rhytidoma). 



There are, besides, a number of plants in which a new layer of liber is 

 annually formed, while the old layer dies away and peels off ; for instance, 

 ritis vinifera, Lonicer« Caprifolium. The bark of dicotyledons consists, 

 therefore, as has been demonstrated in the cases specially examined by Mohl, 

 of three distinct layers, of very different structure, besides the epidermis. The 

 exterior stratum of cells, which, in many cases, changes into a thick corky sub- 

 stance, is called by Mohl the cork layer (stratum siiberosum sen p/i/csiim). Link 

 calls this layer ej^ip/i/iritm, outer rind (oberrinde) ; while he designates the 

 intermediate rind mesopJilceiim, and the inner rind endoplilcEum. The latter 

 may evidently be compared with the layer of liber of other botanists; and the 

 intermediate rind, with the green cellular layer, the so-called cortical pith 

 of many botanists. {Phil, il/flg., Jan. 1838, p. 57.) 



Horticultural Exhibition under the Auspices of the York Philosophical Society. 

 — The council of the York Philosophical Society has announced that an 

 exhibition of plants, flowers, fruits, and vegetables will be held, in the Society's 

 grounds in the city of York, on Wednesday, the 8th of August next, when 

 prizes to the amount of sixty pounds are to be awarded, the competition for 

 which will be thrown open to all England. No individual to be entitled to 

 receive more than one prize in each class. We understantl the coinmittee of 

 management has received very flattering promises of support from the most 

 influential quarters, and that there is every prospect of its being both fashion- 

 ably and numerously attended. It is expected that the exhibition will be of 

 the most splendid description. — //. S. Yorh, June 9. 1838. 



India Rubber, or Caoutchouc, is slightly analogous to silk. It is a re- 

 markable fact, that all the plants the silkworm feeds on contain a larger 

 or smaller quantity of caoutchouc such as the lettuce, dandelion, mulberry tree, 

 &c. In the Brazils, and more particularly in those parts where the India 

 rubber tree (Ficus elastica) abounds, large moths, of from 2 in. to 3 in. in 

 length, producing excellent silk, in large quantities, are very common. 

 From the variety of useful purposes to which India rubber is applicable, 

 (from a lady's watch-guard or stay-lace, to a ship's cable, a great demand 

 has been created for this article, which has induced the mercantile world to 

 bend its attention to it, as a valuable remittance. It is a singular fact, 

 that, wherever the teak tree flourishes, there the India rubber plant may be 

 found in abundance, namely, 20° north and south of the equator. {Xewsp.) 



Antisej^tic Property of Honey. — The best mode of conveying grafts of trees, 

 cuttings of vines, &c., to a distance, is to place them in a tin case or cylinder 



cc 2 



