OF THE BARK. 21 



net-work, and in many instances great regularity and 

 beauty of structure. In a family of plants to which 

 the Mezereon belongs, the fibres of the inner bark 

 have a beautiful white shining appearance like silk. 

 In one of this tribe, a native of Jamaica, and called 

 Lace Bark, that part may be separated by lateral ex- 

 tension into an elegant kind of lace. 



In the old bark of the Fir tribe, on the contrary, 

 nothing of this kind is discernible. The bark of the 

 Cluster Pine, Pinus Pinaster, some inches in thick- 

 ness, is separable 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 Integument ; bu.t they are rather per- 

 haps that vascular part of the Bark which once con- 

 tained 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 neces- 

 sary for the performance of several functions hereafter 

 to be mentioned. 



In the bark the peculiar virtues or qualities of par- 

 ticular plants chiefly reside, and more especially in se- 

 veral of its internal layers nearest to the wood. Here 



