378 



the difference, recorded by Simmoxs (I. c), in the direction of 

 the ripe stems in the two species in question apparently can- 

 not be explained by the anatomical features. The pith was 

 broken down throughout the entire stems. 



The leaf is almost or quite glabrous. The radial walls 



Fig 26. R. nivalis. 



A, Transverse section of leaf. B, Epidermis of the upper surface. C, Epidermis of the 



lower surface. D, Surface section of uppermost palisade-layer. E, Surface section of 



spongy parenchyma. (^4, B, C, D, E are from Kaafjord, Norway; "Vi). 



of the epidermal cells of the upper surface are somewhat un- 

 dulating but less so than those of the lower surface (Fig. 26, 

 B, C). The stomata are on a level with the surface and occur 

 in greater numbers upon the lower surface. The relations 

 between the numbers upon the upper and lower surface is 

 somewhat uncertain; BOrgesen (I.e. p. 229) found 4 and 11 



