FOKMATION OF WOOD 275 



scope miglit be used to a mucli greater extent 

 than up to the present as an aid to classification, 

 and on this point we cannot do better than 

 quote Mr. Herbert Stone, who, in his work on 

 the identification of the timbers of commerce 

 says, " Little attempt has been made to classify 

 woods according to their structure ; yet there 

 are characters which seem to have a distinct 

 systematic value. The primary distinction 

 between the wood of the monocotyledonous 

 trees and that of the broad-leaved trees and 

 the conifers is very definite and well known. 

 The next, between the wood of the two latter 

 groups, is equally emphatic and in accordance 

 with the natural system. Up to this point the 

 structure of wood has long been accepted as 

 being of equal systematic value to that of any 

 other part of the plant. Taking the conifers 

 in their turn, there are reliable differences 

 between the woods of the Pines and their alHes, 

 and those of the Cedars, Cypresses, etc., and 

 there is a further sharp distinction between 

 those coniferous woods with vertical resin 

 canals and those in which they fail. But, when 

 deahng with the wood of the broad-leaved trees, 

 the systematic botanists cannot be followed ; 

 and though characters run through long series 

 of species, genera and even orders, there are so 

 many exceptions that the task of reducing them 



