474 THE BEAN PLANT. [CHAP. 



c,. The Azi-/ 7'csscls : larger elongated cells with 

 oblique perforated septa [siei'e-tubes). 



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



£. 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. p.) 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-7valls; Xhe protoplasm 

 — its presence or absence, and relative f 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. 



/?. The four to six oval leaflets attaclied laterally to 

 the stalk. 



y. The pair of small leaf-like expansions {stipules') 

 at the base of the petiole. 



8. Tlie rudimentary /tv/^/v/ 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, 



