116 PBACTICAL BOTANY. 



2. Their frequent lateral fusion, by means of small 

 branch bundles. 



3. The absence of Stomata above the vascular 

 bundles, and their arrangement in rows in the spaces 

 between them. 



4. The various forms of Hair; and especially the 

 conical unicellular hairs, which give the ciliate character 

 to the margin of the leaf. 



IV. Cut thin tangential sections from the under 

 surface of the lamina, so as to remove, if possible, only 

 the epidermis. Treat with potash, and mount in 

 glycerine. Observe 



1. The ordinary cells of the Epidermis of oblong 

 form, and with sinuous outline. 



2. Short cells between the ends of these, which 

 often project perpendicularly to the surface as Hairs 

 of various form. 



3. The Stomata holding the same position as (2) 

 relatively to the oblong epidermal cells. 



Observe with a high power the structure of the 

 stomata. They consist of 



a. Two narrow guard-cells, which inclose the pore. 



I. Two triangular subsidiary cells, which com- 

 pletely surround the convex side of the guard-cells. 



Compare this view of the storna with the same 

 structure as seen in transverse sections of the lamina. 



V. Cut tangential sections of the upper surface of 

 the lamina. (1). Mount some, and examine them under 

 a low power. (2). Treat others with nitric acid; dry 

 them, and ignite on platinum foil over a spirit lamp. 

 Mount the ash in water, and examine under a low 

 power. The structure will resemble that of (1). 



