eH 
? ( 
‘. 
4, <s x = 
Ly 
a; 
Lie TPS . 
= == 
re, 
Y 
Fic. 67.—Transverse section through the innermost layer of the bark of the oak: p p layer of . 
periderm consisting of thick-walled cells filled with a homogeneous red mass ; 2p ? paren- 
chymatous cells with starch-grains ; s¢? parenchymatous cells with moderately thickened, > 
st with strongly thickened walls ; B g bast-vessels or sieve-tubes ; B £ bast-tubes : B paren- 
chyma and bast-vessels : kr a large parenchymatous cell containing a crystal; x a peri- 
derm-like tissue. (x 440.) os 
