474 THE BEAN PLANT. [CHAP. 



£. The bast vessels : larger elongated cells , with 



oblique perforated septa (sieve-tubes), 

 q. The bast fibres 1 , 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. /3.) 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 ox petiole. 



p. 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 histological 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, 



1 These fibres belong to the central cylinder, but do not, strictly 

 speaking, form part of the bundle. 



