CONSTITUTION AND ARCHITECTURE IN THE CELL WALL 



37 



With the onset of maturation the cell wall commonly becomes 

 encrusted with lignin. The extent of lignification varies, but in 

 the main it is a process associated with intercellular substance 

 and the primary wall. In spruce wood, for example, 60-90 per cent 



Secondary wall inner layer 

 (S3) 



Secondary wall 

 middle layer (S2) 



Secondary wall 

 layer (SI) 



y wal 



Fig. 2. Texture and lamellar arrangement in the cellulose frame of 

 wood fiber cells. (From Wardrop, A.B. and Bland, D.E., The process of 

 lignification in woody plants. Proc. 4th Intl. Congress of Biochem., vol. II, 



p. 96, 1959.) 



of the lignin is present in the intercellular layer, but only 10-12 

 per cent occurs in the secondary wall. In other instances the inter- 

 cellular and primary layers have been reported to consist of 71 



