24 P> >]>K I1TIES OF AVOOD. 



4. Species of Elm (Ulmus). 

 (America, Europe and Asia.) 



Transverse Section. Pores are larger in the spring- wood 

 than in the summer-wood, usually one or two in the radial 

 direction, so that the annual rings are distinct. In the 

 darker mass of the summer- wood, the pores are arranged 



as tangential rows of 

 dots, which, owing to the 

 pores heing bordered by 

 pale parenchyma, appear 

 as peripheral wavy lines. 

 The rays are scarcely 

 visible. 



Radial Section. -- The 

 medullary rays show as 

 gleaming, light brown, short 

 j bands or little streaks 

 among the lighter, slightly 

 lustrous mass of tissues. 

 The borders of the annual 

 zones are distinct, being- 

 represented by the sec- 

 tions of the vessels. The 

 wavy lines of the transverse 

 section appear as fine 

 parallel lines. 



Tangential Section. The 

 cut vessels are the larger, 



the mm ' 





Fig.lS.-Up.ofBlmwood(inmM). 



tangential is the section, 



otherwise as in the radial section. Transverse sections of the 

 medullary niys are scarcely visible, as very line, dark streaks. 

 The vessels and lines of parenchyma, of the summer-wood 

 are distinct as parallel xig/ag lines, somewhat darker than 



their environment (Fig. 13). 



Kims ha\ r e a broad, dark brown heartwood, that on drying 

 rapidly becomes darker. 



