STBrCTUEE. 



51 



on a level with those of the epidermis. In other eases, however, 

 and especially when situated upon leaves of a leathery or hard- 



Fig. 106. 



Fig. 108. 



Fig. 107. 



Fig'. 106. Vertical section of the epidermis of. Leucodendron decorum, show- 

 ing e, e, the epidermal cells, with the stomatal cells, s, with elevated 



margins, m, m. Fig. 107. Vertical section of the epidermis of the Iris. 



s. The stomate. e. Epidermis, p. Parenchyma beneath the epidermis. 

 I. Intercellular space into which the stomate opens. Fig. 10%. Epider- 

 mis of Rnmex acetosa, with rounded stomata, a. Fig. 109. Sauare 



stomate of Yticcagloriosa 



ened texture, the stomatal cells are below the epidermal ones, 

 while in some rare instances again they are above them (fg. 105). 

 The stomata vary in form and position in diflPerent plants 

 and in different parts of the same plant, but they are always the 

 same in any particular part of a plant. The most common 

 form is the oval {Jigs. 92, 93, and 104); in other instances they 

 are round (Jig. 108, a) or square (Jig. 109), They are either 

 placed singly upon the epidermis, at regular (Jig. 92), or irregu- 

 lar intervals (Jig. 108); or in clusters, the intervening epidermis 



Fig. 110. 



Fig. 111. 



Fig. no. Epidermisof the leaf of a species of Saxifrage, showing clustered 



I stomata, .«, with intervening spaces, e, e, in which they are absent. 



Fig. 111. Vertical section of the leaf of Oleander, c. Cavity filled with 

 I / hairs, with stomata at their sides, p. Parenchyma, e. Epidermis. 



having none (fig. 110). In the Oleander (Nerium Oleander) we 

 find little pits beneath the epidermis of the under surface of the 



