PLATE 1 6 



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Periderm of Cascara Sagrada l^Rhaninus purshiana, D.C.) 



yl. I, Outline of cork cells; 2, Line of contact of adjoining cork cells. 



B. Radial longitudinal section of cascara sagrada. i, Cork cells; 2,Phel- 

 logen; 3, Forming parenchyma cells; 4, Cortical parenchyma cells. 



C. 'Cross-secfion of cascara sagrada. i, Cork cells; 2, Phellogen; 3, Form- 

 ing parenchyma cells; 4, Cortical parenchyma cells. 



