EPIDERMIS OF THALLOPHFTES. 121 



internal tissue, and cuticularised on the outer side, or clothed by a cuticle : and even 



FIG 124.— Examples of the forms of hairs. AofPlectiaiithus/rttticosus; B Cajophoya lalei-itia; C Hüraceiim 

 piti/crimi ; D Cheiranthus Cheiri. (After De Bary.) 



in organs where a single layer of cells constitutes the lissue-as in the prothallia 

 of Fejns, the leaves of Mosses, and in many Alg«,— and where, .the vegetative-body 



