i6o 



THE LIFE OF THE PLANT 



Quite a different structure is presented by the stems 

 of conifers and dicotyledons, 1 to which all our forest 



trees belong, such as the 

 oak, lime, maple, etc. In 

 order to understand the 

 structure of these stems, it 

 is necessary to enter into 

 some anatomical details, 

 without which further ex- 

 position of the subject would 

 be useless. 



Botanists, as well as non- 

 botanists, differentiate three 

 parts in the transverse 

 sections of the trunk of a 

 tree : the bark or rind, the 

 wood showing a series of 

 concentric rings and the 

 pith (fig. 45, III.). But 

 botanists go further and 

 distinguish also between the 

 fundamental tissues and the 

 fibrous and vascular bundles, 

 the same distinction as has 

 been already clearly seen in 

 the stems of the mono- 

 cotyledons. Let us try and 

 make this point clear. We 

 . see the predominance of the 

 fundamental tissue in the 

 stem of a monocotyledon ; 

 bundles are scattered in it 

 indiscriminately, and are also surrounded by it. But 

 suppose these bundles were distributed regularly in a 

 circle, and, moreover, were so much developed that 

 only comparatively narrow layers of fundamental 



1 I.e. flowering plants possessing two cotyledons. 



FIG. 45. 



