316 CONSERVATIVE ORGANS. [LECT. VII. 



Horse Chesnut for example, be cut either trans- 

 versely or longitudinally, the parts which have 

 been enumerated, are rendered evident to the na- 

 ked eye. If the section be transverse, it is seen 

 to consist of a central spongy or cellular portion, 

 which is the pith, enclosed within a ring of more 

 solid consistence, which is the wood; and this, 

 again, is environed by another circle of an in- 

 termediate degree of firmness, which is the bark. 

 If the section be longitudinal these parts are seen, 

 in the same order (vide fig. 1, Plate 6), extending 

 the whole length of the shoot ; the pith a. appears 

 like a central column, guarded on every side by 

 the wood b. y and this bounded by the bark c., 

 which forms the exterior envelope of the whole. 

 Running the eye, however, along the section, 

 we perceive that the bark is not continuous ; but 

 where the buds d. e. project, it appears as if re- 

 flected over them, while the exterior fibres of the 

 wood enter into their substance. At the bases of 

 the leaf-stalks,/*, g. this is not the case ; for these 

 appear as if seated upon the bark, connected with 

 the shoot merely by the cords of vessels h. i. which 

 penetrate the wood, and are apparently lost on 

 the surface of the pith. At the summit of the 

 shoot the pith appears to terminate, enclosed by 

 the wood as if by an arch ; whilst the bark still 

 covering the wood mingles with the substance of 

 the leaves which form the terminal bud k. In 



