62 ELEMENTARY BIOLOGY. [VII. 



e. The yellowish tissue (vascular bundles) lying inside 

 and outside the ring of sclerenchyma. 



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

 on the cut surface b. 1. a. b. c. d. 



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

 in water and examine with 1 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 

 fibro-vascular bundles. 



Draw the section. 



4. Examine with -J obj. 



a. The epidermis : its thick-walled cells. 



b. The parenchyma : its large thin-walled cells : their 

 sac, protoplasm and nucleus : the great number of 

 starch granules in them. 



c. The various patches of sclerenchyma, made up of 

 thick-walled angular cells. 



d. The vascular bundles. Note in each : 



a. Outside, a single layer of cells containing no 

 starch-granules (sheath-cells). 



