ee ee ee 
THE ROOT 173 
C. Mount permanently a third T. S. cut through the same 
root a short distance above the second. Note that this is still 
larger in diameter than the second. The pertcambium has already 
divided into an inner and an outer layer. The outer layer has 
become the cork cambium, cutting off the cork on its outer face 
2 x" 
x 
Fic. 105.—Transverse section of California Privet root made about an inch and 
a half above the section shown in Fig. 104 and showing early secondary structure. 
Note that epidermis, primary cortex and endodermis have completely disap- 
peared. Cork (ck); phellogen (pA); secondary cortex (sc); protophloem (p’); 
secondary phloem (#?); cambium (c); secondary xylem (x?) and protoxylem (x): 
(Photomicrograph, X 40.) 
beneath the endodermis. Cork, being an impermeable barrier 
to water, has prevented the nourishing sap from percolating 
through to the endodermis, cortex and epidermis. ‘These 
regions have consequently begun to sluff off. Note that the 
cambium has begun to spread out into the form ofaring. More 
secondary xylem has been formed on its inner face and additional 
secondary phloem has appeared on its outer face (Fig. 104). 
