68 BOTANY 
The cortex consists of fairly large cells, through the 
thin walls of which the nutritive substances can easily 
pass by osmosis from the root hairs to the stele within. 
The stele is enclosed in a single layer of cells the 
endodermis, which, however, it will not with certainty 
be possible to distinguish with a hand lens. 
SECTIONS OF ROOTS 
AUTON 
Vor endodermi 
ml \) y 
*. 
O S 
4 
U 
‘ 
. 
° cy 
ii, 
EPIDERMIS WOOD 
Diagrammatic CORKY BARKS 
SECTION-OF-OLDER-ROOT FIG40— < 
The stele, it will be observed, has four, sometimes 
five groups of rather large openings. These are the 
vessels of the wood, and are really minute tubes which 
pass upwards through the stem and terminate in the 
smallest veins of the leaf. The patches of tissue that 
alternate with these groups form the bast. With an 
ordinary hand lens it is not, as a rule, possible to discern 
the cellular structure of the bast. In the middle of 
