258 



absent. The structure of the hydathode is exactly similar to 

 that, for instance, of S. tiivalis; it does not secrete lime. 



The leaf is consequently very distinctly mesophylic (more 

 particularly hygrophytic), and is presumably the most hygrophi- 

 lous of the three species of the section Boraphila here dealt 

 with, a fact which agrees excellently with its usually very damp 

 habitat; Lazniewski also states that it is: "nicht selten im Was- 

 ser wurzelnd angetroffen" (1. c, p. 246). 



Of this species I have examined specimens from Upernivik 

 (July 18, 1886), Frederikshaab (Aug. 17, 1886), East Greenland 

 (Sept. 4, 1885), Nova Zembla, the Færoe (July 1895), Härjedalen 

 (Aug. 1884), Tromsø (July 21, 1885), — therefore, from widely 

 separated localities; but they all agreed in regard to their structure. 



With regard to the fleshy leaves of the bulbils, see Holm, 

 1. с PI. X, Fig. 6. 



3. Dactyloides. 



The two species of this group which have been investigated 

 agree precisely in (1) the form of the leaves (stalked and pal- 

 mately lobed to palmately cleft), (2) the undulating walls of the 

 epidermis, (3) the distinct differentiation of palisade-tissue and 

 spongy parenchyma, and (4) hydathode with convex epithema, 

 opening upon the upper surface of the leaf slightly within the 

 margin. — The layers of the spongy parenchyma, from the 

 epidermis of the lower surface to beneath the palisade-cells, 

 differ in compactness; immediately within the epidermis the 

 cells are polygonal, without intercellular spaces; higher up, 

 intercellular spaces occur in considerable numbers. The diffe- 

 rence between the two species is most apparent in the extent 

 to which they are hairy. 



Saxifraga hypnoides L. (Figs. 11 and 12). 



Saxifraga hypnoides L. greatly resembles S. groenlandica 

 (see below) in its anatomy. 



