Erythrotrichia Areschoug. 
Phyceae Scandinavicae marinae 1850 p. 209. 
1. Erythrotrichia carnea (Dillw.) J. Ag. 
J. Agardh (1883) p. 15. 
Conferva carnea Dillwyn, Brit. Conf. 1809 pl. 84. 
Conferva ceramicola Lyngb. Hydr. 1819 p. 144 tab. 48 D (teste specim.) 
Banyia ceramicola Chauvin. Rech. sur l’org. de plus. genr. d’Algues, Caen 1842, p. 33; Harvey, Phye. 
Brit. pl. 317: Hauck, Meeresalg. p. 22. 
Erythrotrichia ceramicola Aresch. l.c. p.210; Le Jolis (Thuret), Alg. mar. Cherb. p. 103 pl. Ill fig. 1—2!; 
Berthold (1882). 
This species is attached to the substratum not by means of a basal layer of 
cells, but only by the basal cell which gives off short ramified rhizines radiating 
in all directions on the surface of the substratum, while the other cells of the fila- 
ment produce no rhizines. In fig. 8 C the rhizines are rather irregular as the plant 
was attached to the border of a Porphyra thallus. At the base the filaments are a 
little thinner than higher up, but the outer cell-wall becomes by and by incrassated. 
The filaments often attain only a length of 0,5 cm., but where the plant thrives 
well it becomes at least 3 cm. long. The thickness of the filaments is 16—24 y, 
a little less at the base. 
The cells contain a star-shaped chromatophore with numerous narrow branches 
radiating in all directions, in particular downwards and upwards, and with a cen- 
tral pyrenoid. The nucleus is small and not always visible as it is often hidden 
behind the chromatophore or between its branches (fig. 8 D—F). The vegetative 
cells contain in general no starch; some specimens collected in Sallingsund, Lim- 
fjord, in July were however the exception in this respect, all cells containing nu- 
merous small starch grains staining blue-violet with iodine; yet the sterile cells 
showed not so many starch grains as the sporangia. The length of the cells in 
proportion to the breadth is rather variable. In specimens collected in January 
the cells were very short and their contents very dense; their length was always 
shorter than the breadth, often only a third, while in summer filaments are often 
met with, the cells of which are 3—4 times as long as broad and then with rather 
poor contents. Plants collected on Herthas Flak (Kn) in 19 meters depth in Sep- 
tember consisted of cells of about equal height and breadth. I have only seldom 
met with a few cells divided by longitudinal walls and they gave one rather the 
impression of being somewhat abnormal. BERTHOLD (l.c. p. 25) also found longitu- 
dinal divisions very seldom, while J. AGARDH (I. c. p. 14—15) thought that they 
were common in this species’. : 
This species has only non-sexual reproduction. The spore-mother cell is, as 
well known, cut off by an oblique wall at the upper end of a cell which is not 
different in form from the vegetative cells. Its formation begins with the nucleus 
1 It may be doubtful, whether all that is referred to this species by this author, belongs really 
to it, as for inst. his Tab. I fig. 8, which represents a polysiphonous proliferous filament. 
oF 
