Primulaceae. 



199 



II. multicellular, thickwalled and most frequently branched 

 cover-hairs with a warty cuticle; various forms are depicted 

 in fig. 17, D, E and F; D and E showing the thickness of 

 the walls. Stomates, surrounded by 4 — 5 cells, are present 



Fig. 17. Androsaces septentrionalis. 

 A, the epidermis of the upper surface of the leaf. B, the epidermis of the lower surface 

 of the leaf. C, transverse section of the leaf; the vascular strand to the left shows collen- 

 chyma-like thickened tissue on the lower side. D, E and F, different forms of cover-hair; 

 D and E are seen in optical section. G, epidermal cells from the upper surface of the leaf, 

 with contents of spheroidal formations. (C, obj. 4, oc. 4; the rest, obj. 4, oc. 6.) (öland.) 



on both surfaces of the leaf, but there are about double as 

 many on the lower than on the upper surface, the propor- 

 tion varying only slightly in plants from different habitats. 



