CHAPTER XVI. 



BARK. 



The bark is the external coating: or coverinfr of the 

 stem, branches, roots, and every part of the tree. It 

 consists of three distinct parts or coats. The inner 

 part, next to the sap wood {cdhurnum), is called the 

 libcr, or inner bark, and is the part containing the 

 tannin property used in the manufacture of leather. 

 The next, or central bark, is called the parenchyma, or 

 cork-bark, which, in the stem, branches, twigs, and all 

 parts above ground, is first of a juicy, green colour, 

 very delicate, tender, and sensitive, probably the most 

 tender of any part of the whole structure of the tree. 

 The outer bark of all is called the ejndermis or cuticle, 

 and forms a sort of enamel to the whole structure of the 

 young wood. The liber, or inner bark, is increased an- 

 nually in a manner similar to that of endogenous plants 

 by additional annual layers being added to its inner 

 surface. The liber is fed from the inside, and can some- 

 times be seen and counted very distinctly, the same as 

 the layers of the woody structure of the stem, root, and 

 branches ; and in the case of the larch and pine tribe 

 generally it is most observable and distinct. The 



