THE STEM 209 
2. Cork Campium (phellogen), a layer of delicate cells in the 
process of division with protoplasmic contents. 
2 rer 
(=3 
ei ay a 
CS mr 
ee ; —bf 
= ni J = 
p 
LF = ee ee 
Po is 
=iS-4 eae, 9 285% 
—crf 
A 
te . 
Fic. 139.—Cascara Sagrada Bark. Radial-longitudinal section. &, cork, kk, 
cork cambium; ph, phelloderm of collenchymatous cells; c, primary cortex; st, 
group of stone cells; mp, monoclinic prism; rcr, rosette crystal of calcium oxalate; 
mr, medullary ray; bf, bast fibers; s, sieve tube; , phloem; crf, crystal fibers adhering 
to bast fibers. 
3. CorTEx, or middle bark, consisting of two regions, viz.: an 
outer zone of two or three rows of brownish collenchyma cells, 
and an inner broader zone of tangentially elongated, cortical 
parenchyma cells. Imbedded within this zone will be noted 
numerous groups of stone cells. Rosette crystals and monoclinic 
