188 : PLANT ANATOMY. 
The location of the phellogen is.not exclusively confined to 
the region directly under or within the epidermis, but may also 
develop itself in the form of bands and stripes in the funda- 
_ mental tissue of many barks, or even in the phloém layer. Out- 
side of such layers of internal cork (Fig. 98), the most various 
tissues of the bark may therefore be represented, according to 
the depth at which they lie (phloém elements, Fig. 100, bast- 
cells, Fig. 98, stone-cells, Fig. 101, and, indeed, even resin- 
At il | 
mea zealllili 
Fic. 98,—Transverse section through the bork of Cinchona Calisaya. 8, outermost 
cork layer; r, cork-bands in the inner tissue; J, bast-cells (Berg.). 
canals and oil-spaces, Figs. 99, 100); they become pushed out 
of the course of circulation of the sap by these lamelle of inter- 
nal cork, and are either thrown off as scales (in a very handsome 
manner in the Platanus and Eucalyptus), or they still remain 
for a long time united with the stem, and appear severed and 
_ torn only in consequence of the growth in thickness (207 k, 
thytidoma') ee 
| Puris, Avrisos fold, wrinkle, and Saud I build. 
