228 MINUTE ANATOMY OF FLOWERING PLANTS 



matters which give the cuticle its resistance to water. 



These walls are said to be cutinized. 



528. The pores of the epidermis are called stomates or 



stomata (i.e. mouths). Each stomate (stoma) is guarded, 



so to speak, by two cells of 

 peculiar conformation, called 

 guard cells (Figs. 382, 383, g). 



g g 



382. Section of a leaf : e, epidermis; 383. Surface view of epidermis of 



c, assimilating cells contain- ^^^ l^^j . ^^ o^.^inary epider- 



ing chlorophyll granules; ^^^1 ^^^^. ^^ ^^^^^ ^^^^ _ 



p, intercellular passages ; Tschirch 

 g, g, guard cells of stomate. 



The guard cells, unlike the rest of the epidermis, contain 

 chlorophyll. They are so constructed that as the quantity 



of water they contain varies the slit 

 between them is either opened wider, 

 or narrowed, — or, it may be, quite 

 closed. The guard cells are closed 

 together when flaccid on account of 

 the Avilting of the leaf. 



Stomates are found on most of the 

 green surfaces of the plant, but most 

 abundantly on the leaf. Here they 

 are generally more numerous on the 

 under side. 



529. Trichomes are outgrowths of 



the epidermis, consisting in the sim- 



^„, ^ . , ,, ,, . plest cases of sinoie cells, but in many 



384. Trichomes {h, 70 of ^ ^ "^ 



the leaf. — Sachs, cases of several cclls in a more or less 



