Primulaceae. 



193 



The leaf. The epidermal cells of the upper surface have 

 straight lateral walls, or nearly so, which here and there are 

 provided with flanged thickenings at right angles to the 

 surface of the leaf (e. g. the two upper cells to the right, 

 fig. 14, a). The outer-walls often have fine cuticular striations, 

 especially on the epidermal cells over the midrib. The epi- 

 dermis of the lower surface has undulating lateral walls, 



Fig. 13. Primula nivalis var. puniila. 



A, the central cylinder and the adjoining tissues from a (i-rayed adventitious root; (obj. 8, 



oc. 6). B, the peduncle ; the lig. shows a sector of the transverse section with a vascular 



bundle; (obj. 4, oc. 4). (Pitlekaj). 



provided with thickenings similar to those already described 



for the upper surface; these are especially well-marked 



near the stomates (fig. 14, b). The stomates are exceedingly 



rare on the upper surface, whereas, on the lower surface, 



they are fairly numerous, from 90 — 1 1 per sq. mm ; they 



are surrounded by 4 or 5 cells. Glandular hairs of the usual 



Primula type are present on both surfaces of the leaf, 



and they always originate from an epidermal cell much 



smaller than the surrounding ones (fig. 14, a and b). The 

 xxxvii. 13 



