61 



RosenviDge near the glacier of Kornok, growing on Fucus 

 mßatus, in company with TJlvella fucicola. The plants occur 

 gregariously, almost totally covering the substratum. The fila- 

 ments are 14 — \% fjL thick and the length of the cell varies 

 from Vö to -hà of the breadth. The filaments coalesce below 

 as in the Icelandic plants. The rhizoids are well developed 



Fi£j. 10. 



Fig. 11. 



Ulothrix consociata Wille var. islandica Jônss. 

 Fragments of the specimens from Kornok. 



Fig. 10. a, b, c, The basal portion of three filaments showing rhizoids. 

 d, shows 4 filaments coalescent at the base, a, b, c, d 311 : 1. 



Fig. 11. Transverse section of the frond of Fucus inflatus. The basal 

 layer of the Ulothrix formed by the coalescent basal portions of the filaments 

 covers the surface of the host with an unbroken growth. The rhizoids seem 

 to penetrate the intercellular substance of the host. Beneath the basal layer 

 of the Ulothrix the epidermal cells of the Fucus may be seen in the figure. 

 422 :1. 



and sometimes seem to penetrate the intercellular substance 

 between the outmost cells of the host. The filaments are occa- 

 sionally indistinctly kneed at intervals, and sometimes irregularly 

 constricted. Sometimes the filaments are of an irregular appear- 

 ance, caused by cells growing through emptied sporangia or 

 dead cells. The chromatophore contains one lateral pyrenoid. 



