228 3IINUTE ANATOMY OF FLOWERING PLANTS 



matters which give tlie cuticle its resistance to water 



Tliese 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 CFigs. 382, -383, [/'), 



382. Seetion Ota leaf : e, epidermis; sS'i. Surface view of epidermis of 



Cassimilatingoellscontain- t,,g 1^^.^^ . g_ o,.,,j„,„.y (,pi,,„. 



ing chloropliyll granule,? ; j^^.^, ^.^,1 . ^_ g^.^^.j ^^j, _ 



p, intercellular passages; Tschirch 

 f/, f/, 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 the}^ contain varies tlie 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 wilting of the leaf. 



Stomates arc found on most of tlie 

 green surfaces of the plant, but most 

 al^undantly on the leaf. Here tliey 

 arc generally more numerous on the 

 under side. 



529. Trichomes are outgrowths of 

 the epidermis, consisting in the sim- 

 plest cases of single cells, but in many 



381. Trichomes (h, h) of '- „ , ,, . , 



the leaf. — Sachs, cases ot severaf cells in a more or less 



