385 



chyma. The pith was not broken down. The starch-grains 

 were highly compound. 



The stereom in the stem is weak during flowering but 

 afterwards — when the peduncle elongates greatly — it becomes 

 much stronger: it is about four layers thick between the bundles 

 which, upon their inner sides, are often surrounded by lignified 

 parenchyma and upon their outer sides by strong fibrous 

 tissue. Between the woody part and the inner arch there occurs 

 in the larger bundles a quantity of small-celled, non-lignifled 

 parenchyma (p) as in the majority of the other species ; and be- 

 tween the vessels and the cambium occurs some wood-paren- 



vp 



Flg. 31. В. pygmæus. 



А, Transverse section of rhizome (Spitzbei-gen ; ^^li). B, Portion of transverse section of 



stem (Spitzbergen; "^/i). C\ Stoma from the stem (Danmarks 0; ззод). ep, Epidermis; с, 



cortex; end, endoderrais; Ъ. bast; ph, leptome: vd, lignified parenchyma; x, xylem; p, 



parenchyma; m, pith. 



chyma. The vessels were but slightly developed in the speci- 

 mens investigated, their diameter is small, and they are few in 

 number. The cambium is rudimentary. The bundles number 

 5 — 8. The pith breaks down gradually but entirely (Fig. 31, i^). 



The cortex consists of cylindrical cells and has large 

 intercellular spaces. The stomata are on a level with the sur- 

 face or project slightly (Fig. 31, C) ; the cuticle is slightly 

 striped; chlorophyll is present in the epidermis. 



The leaf nearly resembles in structure that of R. nivalis; 

 thé thickness varies from 270 to 300//. The radial walls of the 

 cells of the upper and lower epidermis are somewhat undulating, 

 those of the lower somewhat more so than those of the upper 



