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, 

 th esoli d i Lj"- and strength 

 of wood depends. The 

 accompanying figure 

 represents a longitudi- 

 nal section of heech, 

 magnified 200 diame- 

 ters. In this g repre- 

 sents dotted vessels ; 

 p, short sells with very 

 abrupt ends; pr, elon- 

 gated cells with oblique 

 ends ; m, sections 

 through the medullary 

 rays, and q, examples 

 of the long anuulated 

 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, iu others, it can scarcely be 

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

 be seen under the microscope. 



m g ra g p qqq 



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

 gent to Kings of Annual Growth. 





53. Dlflferent appearances of the Medullary Rays. 



