oped. It may be analyzed, broadly, as 

 cellulose and lignin, with extractives or 

 infiltrated substances such as resins, 

 gums, tannins, waxes, or the like present 

 to a greater or less extent. 



Cellulose 



Cellulose, the most abundant con- 

 stituent of wood, is also the best known 

 and the most extensively developed in 

 commercial processes. It includes the 

 cottonlike substance of the fiber, which 

 is the basis of refined paper pulps and 



the modern family of products includ- 

 ing rayon, lacquers, cellophane, photo- 

 graphic films, gunpowder, and a long 

 list of nitrate and acetate plastics. 

 This cellulose, although closely related 

 to the simple sugar, glucose, is because 

 of its complex molecular structur^ 

 extremely stable. It is known to exisr 

 principally in the fibrils of the cell 

 wall, but there is associated with it a 

 less stable group of materials amount- 

 ing to almost 40 percent of the total 

 carbohydrate content of the wood and 

 containing pentose sugars and uronic 



M-8534-F, M-7931-F 



Wood fiber structure: Top, Concentric layers 



of the cell wall ; bottom, "sleeve" structure 



revealed by endwise slippage. 





i 



\% ^ 



€1 



M-10296-F (B6). M-10330-F (F1) 



Wood fiber structure: Top, Filamentlike 



winding on outer wall of fiber; bottom, the 



filament removed, showing convolutions. 



12 



