352 Foreign .N'otices. 



apt, from its weight, to burst the bark, and disunite itself from the 

 stock. The stock is headed down, and a notch cut in the end of it, so 

 as to adniir the graft, it being cut in the form of a wedge. We have 

 several small plants in the Oxford garden doing pretty well; and at 

 Moor Park, Hertfordshire, there were, in 1834, several Very fine large 

 plants grafted in this manner. ( W. H. B. — Gard. Mag.) 



FRANCE. 



The Formation of Cork. — M. Dutrochet communicated, at the last 

 meeting of the Academy of Sciences, the results of his observations up- 

 on the formation of cork in various ])lants. Cork is generally supposed 

 to be produced by a superabundance in the layer of cellular tissue, ex- 

 terior to the fibrous layers of the l)ark, as in the Quercus Siiber; but 

 M. Dutrochet states that, according to his observations, this substance 

 has a different origin. The external coating of vegetables is composed 

 of two ])arts: first, the epidermis, or cuticle, an extremely thin mem- 

 brane, without any discernible organization; secondly, of a second mem- 

 brane, composed of small cells, which was for a long time confounded 

 with the e])idermis, but has been very clearly distinguished from it by 

 M. Adolphe Brongniart. This membrane, which M. Dutrochet has de- 

 nominated the tegument or peau cellulaire, increases in thickness by the 

 production of new cells upon its interior surface. Accordinir to him, it 

 is this centripetal development that produces the cork. The paren- 

 chyma of the bark has no share in the production of this substance, un- 

 less we consider it as furnishing liquid nourishment, for the extraordi- 

 nary development of the cellular tissue. It is proved, by this mode of 

 growth, that cork is entirely composed of transverse rows of small cells, 

 of which the oldest are on the outside, and the last formed on the inside. 

 The tissue formed by their assemblage is disposed in layers. Each of 

 these layers corresponds to one year's crowth. 



There is also a variety of the elm which produces cork; but it is only 

 found on the branches, which are from eight to ten years old. After 

 this age the production of cork ceases. It is particularly in this sort of 

 cork, which differs little from that of Quercus Siiber, that M. Dutroch- 

 et has observed the mode of growth of this substance. 



The interior of the prickles upon roses and brambles is occupied by 

 true cork, of the same nature as the preceding. The same is the case 

 in the prickles of Xanthoxylum Juglandifolium. Among monocotyle- 

 donous plants, we find an instance of the production of cork in the Ta- 

 mus elephantipes. It is ujion the enormous rootstock of this plant that 

 the formation takes place; anil it is absolutely the same as other cork. 

 (L'Hermes, Jan. 14, 1837.— Gard. J\lag.) 



A hybrid Jlpple. — M. Legall, president of the Society of Science and 

 Arts of Renness, has made known a ver^' extraordinary instance of hy- 

 bridity. It occurred in a variety of apple sprung from seeds probably 

 fecundated by the pollen of a variety different from that which bore the 

 flower. These apples were grown at the Chateau of Broquignj"; they 

 are very large, and somewhat oblique at their base; of a fine red on 

 one side and A'ellowish or greenish on the other. The two sides are of 

 unequal thickness, and have a ditrorent odor. The flavor is also differ- 

 ent; that of the red side being acid, whilst that of the yellow side is 

 very sweet. It may be called an ajtple formed by the union of lialf a 

 sweet apple, and half a sour appl<>. The seeds are scarcely ever per- 

 fectly developed, as in most hybrids; being commonly reduced to the 

 envelopes, which, however, arc very thick. {Id.) 



