246 



AU the cells of the mesophyll are alike, isodiametric and 

 closely filled with starch-grains. 



There is a solitary vein with a one-layered bundle-sheath 

 devoid of starch. 



The structure of the foliage-leaf and bulb-scale here described 

 I found to be identical with that of the specimens from Mödru- 

 vellir in Iceland, and Egedesminde in Greenland. 



As already mentioned, this species is hygrophytic in its 

 choice of localities. Its anatomical structure is in distinct 

 conformity therewith: Stomata (projecting above the level of 

 the leaf-surface) on both sides; thin epidermis, — in short, 

 no means of protection against excessive transpiration. 



Saxifraga rivularis L. (Figs. 3 and 4). 



Saxifraga rivularis L. is a decided mountain-plant which 

 occurs most frequently on sloping ground, more numerously 

 upon the shady than upon the sunny side. Probably grows 

 usually in damp localities, and in the choice of its localities is 

 almost exactly like S. cernua (Norman, 1. c). 



The leaf is reniform and palmately-lobed, with usually 5 

 lobes, each provided with a hydathode at its apex (Fig. 3 A). 

 Glandular hairs occur sparsely upon both surfaces. 



The epidermis of the upper surface consists of large cells, 

 which have slightly undulating walls and thin lateral and inner 

 walls and irregularly thickened outer walls (Fig. 4). Cuticle thin. 

 Stomata numerous and prominent. Glandular hairs are scattered 

 over the whole surface, but are not abundant. Børgesen (1. с, 

 p. 225) states that the stomata are most numerous upon the 

 upper side, but yet he mentions (1. c, p. 226) having found ,9 

 per unit of surface upon both the upper and lower surface. 



The epidermis of the lower surface is almost exactly like 

 that of the upper, but the cells are somewhat larger, and the 

 walls more undulating talong the veins, however, to a less 

 degree than outside them). (Fig. 4 A, C.) 



