264 



The mesopliyll is distinctly, but not markedly diiïerentialed. 

 The |)alisade-cells are oblique and short. The sporifry paren- 

 chyma is fairly compact; (the section (ignred had been partly 

 torn (hirinfî preparation and has therefore been drawn as more 



iacunose than it was in 

 reality). The cells of the 

 spongy parenchyma are 

 roundly- polygonal, un- 

 branched or very shortly 

 branched. The lowest 

 layer of cells immediately 

 within the epidermis is 

 very compact, without in- 

 tercellular spaces ; the 

 other layers (e. g. midway 

 between the veins and 

 the epidermis of the lower 

 surface) are much looser 

 in texture (Fig. 14). 



The veins — like those 

 in all the previous species 

 — are without mechanical 

 tissue and are surrounded 

 by bundle-sheaths con- 

 taining tannin. The hyda- 

 thodes almost exactly re- 

 semble in structure those 

 of S. hypnoides: they do 

 not secrete lime. 

 The description here given refers to the specimens from 

 Jan .Mayen (July 22, 1896). Somewhat different from these 

 (but otherwise resembling each other) were the specimens from 

 Danmarks (Aug. 6, 1892) and Disco (July 20, 1884), these 



Fig. 15. Saxifraga cœspitosa. 



Epidermis of the leaf. A, Upper surface. B, The 



same (transverse section). C, Lower surface. 



(A, B. C ^k). 



