SELAGINELLA. SPOROPHORE. 169 



as before : the structure will be found to resemble that 

 of the rhizophore. 



If median longitudinal sections be cut through the apex of a 

 root, a root-cap will be seen, which covers an apical cell, 

 having the form of a triangular pyramid. 



VII. Mount some leaves, both dorsal and ventral, 

 which have been previously bleached in alcohol, in 

 water, or dilute glycerine : examine vdth a low power, 

 and observe : 



1. The difference in form of the dorsal and ventral 

 leaves. 



2. The central Midrib. 



3. The ciliate margin. 



4. The characters of the Epidermis ; thus on 



a. The upper surface the cells are small, and 

 circular in surface view, with sinuous lateral walls, and 

 no stomata ; 



&. The cells of the lower surface are elongated, 

 with pointed ends, and sinuous lateral walls ; over the 

 midrib the cells are shorter, and it is there only that 

 the Stomata are found, having two guard-cells, and no 

 subsidiary cells. 



Large chlorophyll grains are to be found in the cells of both 

 the upper and the lower epidermis, and in these the included 

 starch-grains may often be well seen after treatment with iodine. 



VIII. Cut transverse sections of fresh leaves held in 

 a piece of pith : mount in water or weak glycerine, and 

 observe : 



1. The Epidermis of the upper surface (without 



