Fig. 229. Cinchona calisaya - Cross-section of bark.

A, Cork cells. B, Cortical parenchyma. C, Stone cells. D, Phloem portion. E, Soft bast. F, Phellogen forming bark. G, Medullary rays. (The black line from G should be extended to the parenchyma cells between the phloem portions.) H, Bast fibers.
This image is from Cinchona in Sayre's Manual of Organic Materia Medica and Pharmacognosy, 1917.

Fig. 229. Cinchona calisaya - Cross-section of bark.