Bui. 75, Forest Service, U. S. Dept. of Agriculture. 



PLATE IX. 



TRANSVERSE SECTION OF A 2-YEAR-OLD TWIG OF TANBARK OAK, SHOWING TANNIN 

 (DARK STREAKS AND AREAS) IN THE PITH, PITH RAYS, AND BARK. MAGNIFIED 30 

 DIAMETERS. 



