F. Børgesen: Rhodophyceæ of the Danish W. Indies. 



49 



higher up when they have become free of the host plant do they 

 begin to branch. They are multilateraliy ramified and the branches 

 are straight and given off from the axis at an acute angle. 



The principal filaments are thickest 

 near their middle or a little above 

 where the ramification begins ; here the 

 diameter of the cells reaches a length 

 of about 9 /^. At their base the cells 

 are only about 5,5 fi thick. Towards 

 the summit the branches taper^again, 

 the cells here becoming thinner and 

 at the same time longer and with 

 less contents. The cells are cylindri- 

 cal, not constricted at the transverse 

 wahs, in the basal part about 33 [j. 

 long, while near the summit on the 

 other hand their length can reach 

 50// or more. 



The chromatophore (Fig. 49) is 

 parietal, often not much developed 

 and contains a large lateral pyrenoid 

 projecting greatly into the interior of 

 the cell. 



49. Acrochsetiwn Avrainvilleæ nov. 

 spec, a, part of a filament with sporangia. 



Fig. 



Fig. 48. Acrochsetiwn Avrain- 



villeæ nov. spec. Habit of erect ... - - , 



ramified filament with sporan- b, cell with chromatophore and pyrenoid. 

 gia. (About 70:1). (About 600 : 1). 



The monosporangia (Figs. 48, 49) are sessile or more rarely 

 pedicellate, usually occurring on the inner side of the branches 

 near their base, seriate or a few together; but sometimes more 

 irregularly. 



Dansk Botanisk Arkiv, Bd. 3. Nr. \ (1915). 4 



