68 



Structure of Wood. 



in their season sap, and others the resinous or other secretions of 

 g m pr g p pr the tree. Upon the 



length and adherence 

 of these various vessels, 

 thesolidity and strength 

 of wood depends. The 

 accompanying figure 

 represents a longitudi- 

 nal section of beech, 

 magnified 200 diame- 

 ters. In this g repre- 

 sents dotted vessels ; 

 _p, short cells with very 

 abrupt end?; pr, elon- 

 gated cells with oblique 

 ends ; m, sections 

 through the medullary 

 rays, and q, examples 

 of the long aunulated 

 cells appearing in the sections like rows of spots. 



244. Different kinds of wood exhibit the radiating structures due 

 to the medullary rays in different degrees. In some, it is very con- 

 spicuous in the cross-section, while, in others, it can scarcely be 

 traced by the eye, except in thin cross-sections, although always to 

 be seen under the microscope. 



S q S m g P qqq 



52. Vertical Section of Beech Wood, in a Plane tan- 

 gent to Rings of Annual Growth. 



53. Different appearances of the Medullary Rays. 



