38 
PHARMACEUTICAL BOTANY 
xylem mass surrounded by an outer phloem mass. Each bundle is 
enveloped by a pericambium and an endodermis or bundle sheath. 
Histology of Lamina. —In transverse and surface sections the 
lamina or blade shows the following structural details: 
i. Upper epidermis, of wavy-walled, slightly chlorophylloid, flat 
upper epidermal cells, devoid of stomata, but with rather thick 
cuticle. 
Pig. 15. —Transverse section of stipe of Dryo-pteris Filix-mas showing epi¬ 
dermis (e); hypodermis (h); inner cortex (t'c); concentric fibrovascular bundles, 
one of which is shown at (&); endodermis ( en); pericambium {p); xylem ( x); 
and phloem (p). (Photomicrograph.) X 50.4. 
2. Mesophyll, of irregular shaped chlorphylloid cells, containing 
abundant chloroplasts. Intercellular-air-spaces are found between 
various cells which are larger in the lower than in the upper region. 
Internal glandular-hairs are frequently to be discerned in many of 
these spaces. 
3. Concentric vascular bundles or laminar veins, that distribute 
sap to, and carry sap from the mesophyll. These are seen to be 
