XEROPHVrES AND ITALOPHYTES. 



321 



ment of two or more layers of epidermal cells (fig. 370) ; or 

 the excretion of wax or of varnish upon the surface of the epi- 



FiG. 359. — Transverse section of :i leaf of a heath {Tylanthus ericoidcs), showing 

 revolute form. The stomata are on the under (concave) surface among the hairs, 

 which still further impede the tr^mspiration. Magnified 13a diam. — After Kerner. 



dermis. The latter often becomes very thick, giving to the 

 leaves a shiny appearance. Wax is usually in the form of a 



Fig. 360. 



Fig. 362. 



Fig. 360. — Prickly pear {'^/'imiin -^'-ulgaris) \^\\h flattened jointed stem and no 



leaves. About one fourth natural size. — After Frank. 

 Fig. 361. — Multicellular hairs of edelweiss. Magnified about 50 diam. — After Kemer. 

 Fig. 362. — Silky unicellular hairs of Con-uo/vuius L'neorunt. Magnified about 50 



diam. — After Kemer. 



