222 



FIKST BOOK OF FORESTRY 



FIG. 81 



FIG. 80 



FIG. 80. Spiral Grain. 

 (Season checks, after 

 removal of bark, indi- 

 cate the direction of the 

 fibers or grain) 



FIG. 81. Shortleaf Pine. 

 (Cross section of parts 

 of two rings) 



sp.iv., spring wood with thin 

 walls; su.w., summer wood 

 with thick walls. The cells 

 run in rows which extend 

 through several rings. (Mag- 

 nified about 70 times) 



The ring-porous 

 woods, like oak, ash, 

 chestnut, locust, 

 elm, hickory, etc., 

 where the ring is 

 defined by a line 

 of large pores in 

 the spring wood. 



The diffuse- 

 porous woods, like 

 maple, yellow pop- 

 lar, and cherry, 

 where the pores are 

 usually very small 

 and evenly scat- 

 tered through the 

 annual ring. 



The non-porous 

 woods, like pine, 

 spruce, hemlock, 

 and all our conif- 

 erous woods. 



Pith Rays. 

 Looking at a cross 

 section of a log or 

 piece of oak, we 

 observe broad lines 



