viz.] THE BRACKEN FERN. 63 



b. The rhizome. 



T. Cut it across and draw the section as seen with the 

 naked eye. 



a. The outer brownish layer (epidermis and sub- 

 epidermis] ; the latter thins away somewhat, 

 opposite the lateral lines. 



b. The yellowish-white substance (ground-substance 

 or parenchyma) forming most of the thickness of 

 the section. 



c. The internal incomplete brown ring (sclerenchyma} 

 imbedded in the parenchyma. 



d. The small patches of sclerenchyma scattered 

 about in the parenchyma outside the main 

 sclerenchymatous ring. 



e. The yellowish tissue (vascular bundles] lying in- 

 side and outside the ring of sclerenchyma. 



2. Cut a longitudinal section of the rhizome ; make out 

 on the cut surface b. i. a, b, c, d. 



3. Cut a thin transverse section of the rhizome, mount 

 in water and examine with i inch obj. 



a. The single layer of much thickened epidermic 

 cells. 



b. The small opaque angular contours of the sub- 

 epidermic cells (external sclerenchyma). 



c. The large polyhedral more transparent paren- 

 chymatous cells. 



d. The small opaque angular contours of the cells 

 of the internal sclerenchyma. 



e. The great openings of the ducts and vessels in 

 the nbro-vascular bundles. 



Draw the section. 



