Cir. 215, Fo-est Se-^':e. U. S. Deot. o' Agr 



Plate 



Fig. 1 .—Transverse Section of a Branch of River Birch. Showing Pith Flecks. 



Natural Size. 



Fig. 2. -Tangential Se. 



nc TrsuNrN \jr On 



Natural Size. 



iH'i_t, Onu.NiNo rii- r^:i^>\s. 



