WOOD OF BROAD-LEAVED TREES 



27 



that we find the greatest complexity and variety. This may con- 

 tain from three to five of the following six kinds of elements : 

 tracheids, vessels, woody fibres, fibrous cells with thick or with 

 thin walls, and wood-parenchyma. The trachece or true vessels 

 vary considerably in transverse diameter, some of them being the 

 widest pores seen in a transverse section of wood and being some- 







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times specially conspicuous in the spring-wood. Some of them, in 

 young wood, have net-like thickening, but most of them have 

 bordered pits, as have also the tracheids. The chief differences in 

 fact between these two kinds of elements are the smaller diameter 

 and lesser length of the tracheids. As they are each formed from 

 a single cambium-cell, these tracheids have no transverse divisions ; 



