170 PHARMACEUTICAL BOTANY 
9. Strands of cells extending radially from the cortex to the 
center of the section separating each open fibro-vascular bundle 
from its neighbors, These are called medullary-rays. 
The xylem or wood portion of each fibrovascular bundle 
appears as a wedge placed between the xylem portions of two 
medullary-rays and so is sometimes called a Woop Wepcr. The 
xylem portions of the medullary-rays between the wood wedges 
are termed Woop-rays. 
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Fic. 102.—Photomicrograph of a transverse section of a California Privet root 
of primary growth showing epidermis (ep); hypodermis (h); primary cortex (fc); 
endodermis (en); pericambium (ca); a xylem arm of the radial bundle (x); a phloem 
arm (ph); and pith (m). x 40. 
HistoLoGy AND DEVELOPMENT oF A TypicAL Dicotyit Root 
(CALIFORNIA PriveT).—A. Make a permanent mount of a cross 
section of the root of the California Privet (Ligustrum Californicum) 
cut just above the root cap, and note the following structures, 
passing from periphery toward the center (see Fig. 102): 
1. Epidermis, composed of a layer of epidermal cells whose 
outer walls have been infiltrated with a substance called cutin. 
2. Hypodermis, a layer of somewhat thick-walled cells just 
beneath the epidermis. 
3. Cortex, composed of cortical parenchyma cells with small, 
angular, intercellular-air-spaces. 
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