281 



morphological and anatomical structure has a great many points 

 in common with that of S. Cotyledon (e. g. the succulent leaf- 

 rosettes, the external form of the leaf, etc.). 



The epidermal cells of the upper surface (Figs. 25 5 and 27) 

 of the leaf are elongated longitudinally at the base, but higher 

 up in the leaf they become transversely elongated. The outer 

 walls are thick, with distinct cuticle. The stomata are absent 

 from the leaf-bases, they do not appear until above the 



Fig. 26. Saxifraga Aizoon. 



The leaf: A. Spongy parenchyma. B, Transverse section (below to the left, a tannin-cell, 



to the riglit a sphaerocrystal). (A, B, -W/i). 



marginal hairs. They are surrounded by, usually, four smaller 

 cells (cf. Thouvenin 1. c.) and are not definitely orientated 

 (e. g. not parallel with the midrib). 



The lower epidermis (Fig. 27) is of elongated cells at the base 

 of the leaf and is continued as a median band of similar elongated 

 cells without stomata, which gradually narrows towards the apex 

 of the leaf. To the right and left of this band occur areas which 

 are of smaller cells, and there all the stomata are placed in 



