118 



THE BIOLOQT OF A PLANT. 



FIG. 49. Section showing the epidermis (ej>) and the underlying sclerotic paren- 

 chyma (s.p) of the rhizome of Pteris cufuilina. Canals, sometimes branching, are 

 everywhere seen. These served to keep the once-living cells in material con- 

 nection. 



Fio. 50.-Cross-section of sclerotic prosenchyma of the rhizome of Pteris aquttina. 

 The enormously thickened walls consist of three layers, are perforated by canals, 

 and are UffnAfled or turned into wood 



