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



PHÆOPHYCEÆ 



I. Phæosporales. 



Farn. 1. Ectocarpaceæ. 



EctO CarpUS Lyngb. 



1. Ectocarpus Duchassaingianus Grun. 

 Grunow, A., Ålgæ, in »Reise der Österreichischen Fregatte Novara um 

 die Erde«, Botan. Theil, Ister Bd., 1870, p. 45, tab. IV, fig. 1. 

 Vickers, A., Phycologia Barbadensis, Part. II, tab. 27. 



To this species of Grunow I have referred an Ectocarpus 

 which seems to agree with it very well even if there are a few 

 differences. 



It occurs as rather large 2 — 4 cm high tufts growing epiphytic- 

 ally upon other algæ or on stones, piles and similar substrata in 

 harbours or bays. 



The basal part consists of rather thick-walled, yellow-brown, 

 irregularly bent and ramified, rhizoid-like filaments woven together 

 (Fig. 2 a). From this basal part the erect filaments grow up. At 

 first the filaments increase by division of all the cells but soon 

 marked intercalary growth takes place (comp. Fig. 1 and 2 c); 

 the filaments terminate in rather long, nearly colourless hairs, the 

 uppermost cells of which reaching a length of 5 — 6 times their 

 own breadth. Elsewhere the cells in the filaments are 1 — 2, 

 sometimes even 3 times, as long as broad. The diameter of the 

 cells reaches 20 — 22 p. 



The ramication is spreading and very irregular; often large 

 parts of the filaments are not ramified at all (Fig. 1). 



The chromatophores consist of small, irregularly shaped discs, 

 often roundish, or in the younger cells, oval (Fig. 2 g). 



The plurilocular sporangia are as a rule sessile (Fig. 1 and 

 Fig. 2 b, c), occasionally they are found ending a short branch 

 (Fig. 2 e). They are very variable in size and form; sometimes 

 long and nearly cylindrical (Fig. 2 b), sometimes short and often 

 clavate and with walls more or less undulating. They may reach 

 a length of more than 250//, most commonly they are only the 



