(Rhamnus Purshiana). (X 210.) col, Collenchyma of the cortex. cr, Prismatic and rosette crystals. fi, Bast fibers. l, l', Bast in longitudinal and transverse sections. pc, p'c', Cortical parenchyma in longitudinal and transverse sections. ph, Phelloderm. rm, Medullary rays, tangential section. r'm', The same, transverse section. r''m'', The same, radial section. s, s', Cork, in surface view and section. sc, Sclerenchymatous cells. tc, Rows of crystal cells.—(From Greenish and Collin.) This image is from Drug Powders (also see Cascara sagrada) in Sayre's Manual of Organic Materia Medica and Pharmacognosy, 1917.