Bui. 606, U. S. Dept. of Agriculture. 
Plate II. 
Red Oak (Cross Section, Magnified 50 Diameters^ A Ring-Porous Wood. 
AB, annual ring; SP, springwood: SW, summerwood; MB, medullary ray; T", pores or vessels; 
X, vrood prosenchyma (fibers, etc.). 
