WOOD OF BROAD-LEAVED TREES. 35 



Linden, Magndlia, Ailant/ms, Robinia, etc., contains vessels, 

 tracheids, woody fibre, thin-walled fibrous cells, and wood- 

 parenchyma. 



The distinctive features of woods, however, depend rather 

 upon the proportions in which these elements are present and 

 upon their arrangement than upon the absen.ce of any of the six 

 kinds of elements. There is, as a rule, among the woods of 

 broad-leaved trees no such regularity of radial arrangement of 



FIG. 26. Transverse section of Beech (F&gnx sylrdtica). Magnified 100 

 times, a, narrow pith-ray ; 6, broad pith-ray ; c, boundary of an annual 

 ring. The large pores are transverse sections of vessels (tracheae). The thick- 

 walled elements with narrow lumina are wood-fibres ; those with thinner 

 walls and wider lumina, wood-parenchyma or tracheids. From Hartig"s 

 Timbers and how to know them, by permission of Dr. Somerville and Mr. David 

 Douglas. 



elements as characterizes the simple wood of conifers. In the 

 cambium region, it is true, owing to the repeated regular tangen- 

 tial divisions, the cells not only appear rectangular in a transverse 

 section, but are also in regular radial rows ; but in the xylem 

 itself this regularity is disturbed by the different diameters 

 attained by the various elements as they become fully formed. 

 In Oak, for example, the annual rings are marked in a cross- 

 section by the large and conspicuous pores, or sections of the 



