4/4 THE BEAN PLANT. [CHAP. 



. The bast vessels: larger elongated cells with 



oblique perforated septa (sieve-tubes], 

 rj. The bast fibres, fusiform and thick-walled. 



c. More parenchymatous cells, constituting the cortex. 



d. Epidermis: composed apparently of cubical colour- 

 less cells : here and there the opening of a stoma 

 (d. 2. d. ft.) may be seen. 



Draw the section. 



5. Compare the transverse and longitudinal sections 

 together, making out the corresponding parts in each. 



6. Put on a high power, and examine each of the 

 above-mentioned tissues carefully. 



7. Stain with iodine : note the cell- walls; the protoplasm 

 its presence or absence, and relative quantity in 

 the various tissues ; the nuclei of the cells ; starch 

 granules in some, stained deep blue by the iodine. 



d. The leaves. 



1. Their form and composition. 



a. Each leaf consists of a number of different parts, 



viz. : 



a. The stalk or petiole. 

 ft. The four to six oval leaflets attached laterally to 



the stalk, 

 y. The pair of small leaf-like expansions (stipules] 



at the base of the petiole. 

 8. The rudimentary tendril terminating the petiole. 



2. The histo logical structure of a leaflet. 



a. Imbed a leaflet in paraffin or hold it between two 

 bits of elder pith and cut a thin section from it, 



