114 PRACTICAL BOTANY. 



Transverse sections should also be cut immediately below the 

 apical tuft of leaves. Here the secondary thickening will not have 

 begun, the arrangement of tissues resembling, in all essential 

 points, that in the internode of the Maize. 



LEAF. 



Note the phyllotaxis in the Maize ; the leaf is sessile, 

 and sheathing in its lower half, with a ligule at the 

 apex of the sheath ; lamina, form lanceolate, margin 

 entire, ciliate, midrib well marked ; venation parallel ; 

 upper surface hirsute ; lower glabrous. 



I. Cut transverse sections of the lamina ; mount in 

 water, or dilute glycerine. 



Other sections may be treated with alcohol to expel the air 

 bubbles (the chlorophyll will, at the same time, be dissolved out), 

 and be mounted in Schulze's solution, and kept for comparison 

 with the above. 



Examine with a low power. 



The section presents a sinuous outline, correspond- 

 ing to a certain extent to the arrangement of the 

 main vascular bundles. At the mid-rib the section 

 widens out. Note the following arrangement of 

 tissues : 



1. Covering both surfaces of the leaf is an Epidermis, 

 resembling that of the stem, but bearing hairs of 

 various form, mostly simple, conical. The largest 

 of them are surrounded at the base by an outgrowth 

 of the neighbouring epidermal cells. 



Note the Stomata on both surfaces, with small 

 guard cells, surrounded by two subsidiary cells (cf. 

 infra). 



2. Vascular Bundles of various size, which, in the 



