CHAPTER VIII. 



THE CORTEX AND BARK OF TREES, 



If we turn our attention for a moment to the 

 illustrations in the first chapter, it will be remembered 

 that our typical log of timber was clothed in a sort of 

 jacket termed the cortex, the outer parts of which 

 constitute what is generally known as the bark This 

 cortical covering is separated from the wood proper by 

 the cambium, and I pointed out (pp. ii and 12) that 

 the cells produced by divisions on the outside of the 

 cambium cylinder are employed to add to the cortex. 



Now this cortical jacket is a very complicated 

 structure, since it not only consists of numerous 

 elements, differing in different trees, but it also under- 

 goes some very curious changes as the plant grows up 

 into a tree. It is beyond the purpose of this book to 

 enter in detail into these anatomical matters, however ; 

 and I must refer the reader to special text-books for 



