BORK—CORK. 191 
also capable of forming bork, which may be very plainly observed, 
for instance, in Radix Sassafras. 
If the periderm layers which are formed in the interior of the 
bark occupy only a part of the circumference, scale-bork is pro- 
duced (Robinia, Platanus, Cinchona, Pinus silvestris, Quer- 
cus); if, however, the secondary periderm layers form parallel, 
Fia. 103.—Transverse section of Rhizoma Curcume; s, cork. 
closed rings, which embrace the entire circumference, hollow- 
cylindrical sections of bark are converted into bork, and ringed- 
bork is produced ( Vitis, Clematis). 
Fic. 104.—Cortex Cascarille. Cork layer and primary bark, with crystals of calcium 
oxalate and coloring matter. 
Since the cork-cells are produced by a tangential division of 
mostly tangentially extended cells, they are flatly tabular and 
parallelopipedal. They are in unbroken connection with each 
other and contain air, never solid matter. As the divisions in 
the phellogen take place very regularly, the transverse walls of 
the cork-cells frequently traverse the entire cork tissue In one 
and the same line (Figs. 102, 103, 108). 5 
