182 



Cellulose 



of the Dicotyledoneae in regard to this constituent or group 

 of constituents, and an equally striking divergence in the case 

 of the woods of the Coniferae. This differentiation of the 

 Coniferae will be dealt with in the section devoted specially to 

 the group (p. 197). 



De Chalmot has further investigated the question of the 

 life-history of the woods in reference to this group of con- 

 stituents, and has established the important conclusion that 

 they preserve a more or less constant ratio to the entire wood- 

 substance. The determinations were made upon the wood of 

 particular and successive rings in horizontal sections, the posi- 

 tion of the rings in the section determining the age of the wood- 



