78 



unaltered sporangial membrane. In the treatise on the Bangiacece by the same 

 author (1896), however, tliese characters are not mentioned; the author states only 

 some less essential differences and declares that at least A. ramosa might possibly be 

 referred to the genus Goniotrichum. In 1900 Wille has given a more detailed 

 description of an Alga which he had found at Mandal on the South coast of Nor- 

 way, and which he refers to the same species. He gives a description of the set- 

 ting free of the spores which is in accordance with that of Schmitz in 1894, but 

 apparently without knowing the treatise of Schmitz, and he recommends that the 

 genus Asterocytis should be kept distinct from Goniotrichum, primarily on account 

 of the blue-green colour, but also because the author supposes that it produces 

 resting cells, akinetes. It seems further that we may add as a distinctive character, 



that Asterocytis ramosa grows in brackish 

 water, as stated by several authors (Har- 

 vey, Hauck, Schmitz, Batters), while Go- 

 niotrichum elegans needs water of higher 

 salinity. 



I have found in several localities 

 in the inner Danish waters a small Alga 

 with blue-green cells, undoubtedly be- 

 longing to this species. It occurred, 

 however, as a rule in small individuals, 

 most frequently even unbranched, and 

 in such cases agreeing with Goniotrichum 

 simplex Lakowitz. Some of these speci- 

 mens were short and only 9 — 11 fi thick, 

 with vegetative cells 3 — 6/u broad. Others 

 were longer and somewhat thicker be- 

 low, and the most vigorous provided 

 with one or a few branches. Such spec- 

 imens had often a thickness of 16 « 

 near the base, in a single case of 25 ;x\ the vegetative cells were about of the 

 same size as in the smaller specimens, or they might be up to 7,5 /j. broad. In 

 the plants examined by Wille the cells were, to judge from his figures and the 

 magnification indicated, not a little greater (8 — 11,5/i broad), and the plants were 

 as a whole more vigorously developed. In the Danish specimens the cells are 

 usually oblong or ellipsoidal, often ca. 2 times as long as broad, sometimes shorter, 

 nearly globular. The chromatophore, as is well known, is star-shaped with a dis- 

 tinct pyrenoid; this, however, is not always central in the cell, the chromatophore 

 being often nearer to the one side of the cell (fig. 17 B). 



The occurrence of akinetes supposed by Wille I have been fortunate enough 

 to confirm with certainty. In nearly all my gatherings of this species there was 

 found a number of filaments, the cells of which were for the most part transformed 



Asterocytis ramosa [t'l otn Guldborgsund). A, filament with 

 branch; in some cells the pyrenoid is shown. B—D, small 

 unbranched filaments with akinetes. 220:1. 



