22 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 
somewhat uncommon in yellow birch, although the writer has found 
them from time to time in propeller stock of this species. Softwoods 
Fic. 8.—Transverse section of a branch of river birch, showing pith-ray flecks. Natural size. 
Fic. 9.—Tangential section of the trunk of a tree of silver maple, showing pith-ray flecks. 
Natural size. 
