376 



Diptera (Ekstam). Lindman has proved by experiment that it sets 

 ripe fruit after self-polHnalion. The flowering begins in the 

 middle of June, and the fruit ripens in August. Ekstam (1897) 

 did not find ripe fruit in Nova Zembla, but records such from 

 Arctic Siberia. He states that the fruit is dispersed by the 

 agency of the wind. Norman thinks that reindeer are concerned 

 in Arctic Norway with the dispersal of the fruit. 



According to A. Cleve (1. c.) B. nivalis germinates during 

 autumn (December), but seeds which had been sown by Sylvén 

 in flower-pots germinated during the following spring. In the 

 first stages of ils development R. nivalis resembles R.pygmœus, 

 but is distinguished from the latter by less decided hetero- 

 phylly. The two cotyledons are long-stalked, the lamina is 

 oval-lanceolate, and the sheaths are coherent at their base. 

 The primordial leaf is tripartiteiy lobed in front (Sylvén). 



During the first weeks of the period of vegetation in 

 spring, B. nivalis appears to require a cold soil, wetted by 

 melting snow, but afterwards the soil may become dry without 

 injury (Cleve, Norman). In Spitzbergen the plant grows both 

 upon grassy slopes and also in marshy ground, and at Scores- 

 by Sound in East Greenland in damp clay. In Norway it is 

 a markedly continental plant that may extend very high up into 

 the mountains (1550m. above sea-level); in East Greenland it 

 is not very probable that it will be found at the heads of the 

 of the fjords (Norman, Hartz, Dusén). 



Geographical Distribution. (Holm). Arctic America, 

 Greenland, Spitzbergen, Scandinavia, Arctic Russia, Nova 

 Zembla, North Siberia. 



Anatomy. The structure of the root (Fig. 25, /3, B) 

 was similar in specimens investigated from all the regions 

 from which I had material, and did not difter in any essential 

 points from that of the root of B. glacialis. The epidermis 

 has a tendency to collapse, both it and the exodermis are 

 suberized. From one to two of the outermost layers of the 



