190 PLANT ANATOMY. 
Whether barks experience the formation of bork, or are pro- 
vided with a simple covering of cork, appears to depend upon 
A 
fi 
Ke 
Hf 
Aheet arte 
Fie. 101.—4, Cork of the cork-oak; aa, cork-cells; bb, stone-cells; B, more highly 
magnified cork-cells, 
Ee ane a f 
se ae " : oy 
— - — 
~ : ae ee. — 
= =" oe 4 x 
3 Lag. 2 
o 4 
~ OR, & % a ¢ 
Lee 7! POT, 20 0, 0G 7 aly 
f Gs" fo, Ooo *, 
\ 
vis 
R 
aN 
Fic. 102.—Cortical layer of Radix Calumbe; s, cork; m, fundamental tissue, with dis- 
persed stone-cells which inclose crystals of oxalate; R, 7, More highly magnified 
crystals; H, twin crystal. 
the peculiarities of the species. In the Cinchonas, for exam- 
ple, bork is sometimes met with, and sometimes not. Roots are 
