14 
PHARMACEUTICAL BOTANY 
2. Outer cortex (hypodermis), a zone of several layers of thick- 
walled lignified cells separating the epidermis from the inner cortex 
beneath. Its main function is to support the epidermis. 
Fig. 2 . — Dryopteris filix-mas — Plant and section through pinnule and sorus. 
{Sayre.) 
3. Inner cortex of several layers of more or less isodiametric cells 
with thin cellulose walls and containing stored starch surrounded by 
a protoplasmic investment. These cells conduct sap by osmosis and 
