118 PKACTICAL BOTANY. 



shaped, and surround the nearly circular pore. The 

 cells of the epidermis remain ohlong as before. 



It will be seen that; the stoma of Hyacinthus is of simpler 

 structure than that of the Maize. It is more difficult to trace the 

 development of the latter ; but it may be done in the same way 

 in a foliage bud. The main point of difference is that after the 

 mother-cell of the stoma has divided to form the two guard-cells, 

 two other cells are cut off from the neighbouring epidermal cells 

 (subsidiary cells). These lie parallel to the guard-cells. 



Further, the epidermis of the Maize is complicated by short 

 cells, which appear in irregular groups among the ordinary 

 epidermal cells. This is a common character among the Grasses. 



BOOT. 



1. Cut transverse sections of the root of Hyacin- 

 thus orientalis. (N.B. An old root must be taken, 

 and the sections should be cut as far as possible from 

 the apex). Treat them with potash, and mount in 

 glycerine. Starting from the outside, note succes- 

 sively 



' 1. An Epidermis, not well marked. Note here and 

 there cells, which have grown out perpendicular to the 

 surface as root-hairs. 



2. A thick band of Cortical parenchyma, consist- 

 ing of rounded cells with intercellular spaces ; in old 

 roots the outer layers of this tissue become disorganised 

 and distorted. The inmost layer of this tissue differs 

 in structure from the rest, and is called 



3. The Bundle-sheath : the radial walls of this 

 layer present the characteristic appearance of a black 

 dot, and are cuticularised. Within this is 



4. A layer of thin- walled cells (the Phloem-sheath 

 or pericambium), which immediately surrounds 



