456 ELEMENTARY BIOLOGY. [CHAP. 



b. The mesophyll, the cells of which contain chloro- 

 phyll-grains in large numbers. 



c. The transverse sections of the vascular bundles. 



2. Slice off the epidermis from the under side of a leaflet. 

 Mount in water and observe with a high power 



a. the ordinary epidermal cells of irregular form, 



b. the hairs, 



c. the stomala, each stoma with its two kidney-shaped 

 guard-cells. 



d. The root. 



i. Examine the tip of an uninjured root with a lens ; note 

 the relatively large root-cap covering the end of the 

 root. 



2. Make a transverse section of a mature root held in 

 elder-pith, or imbedded in paraffin. Note, under a low 

 power, 



a. the epidermis with its root-hairs, 



b. the cortex consisting of parenchyma towards the 

 outside, and of very thick-walled sclerenchyma 

 nearer the centre, 



c. the central vascular cylinder. 



e. The reproductive organs. 



i. Examine a sorus with a low power without a cover- 

 glass. It is composed of a great number of minute 

 oval bodies, the sporangia, roofed in by the indusium. 



2. Scrape off some sporangia and mount in water : ex- 

 amine with i inch obj. 



a. Their form : they are oval biconvex bodies 



borne on a short stalk. 

 J). Their structure: composed of brownish cells, one 



row of which has very thick walls, and forms a 



