OF THE BARK. 39 



that part may be separated by lateral extension into an 

 elegant kind of lace. 



In the old birk of the Fir tribe, on the contrary, noth- 

 ing of this kind is discernible. The bark of the Cluster 

 Pine, Pinus Pinaster^ some inches in thickness, is sepa- 

 rable into thin porous layers, each of them the production 

 of one season, which do really seem to be, according to 

 M. Mirbel's theory, hardened and dried Cellular Integ- 

 ument ; but they are rather perhaps that vascular part of 

 the Birk which once contained the secreted fluid, or 

 turpentine, so abundant in this tree. 



The bark of Oak trees twenty or thirty years old, if 

 cut and long exposed to the weather, separates into 

 many fine thin layers, of a similar, though less delicate, 

 texture to the Lace Bark of Jamaica. All these layers, 

 in a living state, are closely connected with each other by 

 the cellular texture which pervades the vegetable body in 

 general, as well as by transverse vessels necessary for the 

 performance ofseveral functions hereafter to be mentioned. 



In the bark the peculiar virtues or qualities of partic- 

 ular plants chiefly reside, and more especially in several 

 of its internal layers nearest to the wood. Here we find 

 in appropriate vessels the resin of the Fir and Juniper, 

 the astringent principle of the Oik and VVillow, on 

 which their tanning property depends, the fine and valu- 

 able bitter of the Peruvian Bark, and the exquisitely ar- 

 omatic oil of the Cinnamon. The same secretions do 

 indeed, more or less, pervade the wood and oiher parts 

 o{ these plants, but usually in a less concentrated fo; m. 



When a portion of the bark of a tree is removed, the 

 remainder has a power of extending itself laterally, 

 though very gradually, till the wound is closed. This 



