. Dansk botanisk arkiv. Plants; Plants -- Denmark. F. Borgesen: Phæophyceæ of the Danish W. Indies. 7 or larger algae, e. g. Codiam. The rhizoids are about 11/^ thick and consist of proportionately long cells. In the basal part the main filaments are thinner, reaching only a thickness of about 22 y.; higher up they grow thicker, the diameter of the cells here being from 35 —45, seldom 50 j«, while their length is about 2—3 times as long. In the upper part of the thallus the filaments become thinner again, the cells at the same time becoming proportionately longer. The cells are cylindrical or
. Dansk botanisk arkiv. Plants; Plants -- Denmark. F. Borgesen: Phæophyceæ of the Danish W. Indies. 7 or larger algae, e. g. Codiam. The rhizoids are about 11/^ thick and consist of proportionately long cells. In the basal part the main filaments are thinner, reaching only a thickness of about 22 y.; higher up they grow thicker, the diameter of the cells here being from 35 —45, seldom 50 j«, while their length is about 2—3 times as long. In the upper part of the thallus the filaments become thinner again, the cells at the same time becoming proportionately longer. The cells are cylindrical or sometimes very slightly barrelshaped; in the lower part of the thallus their walls are often brownish coloured. The lowermost parts of the main fila- ments are not ramified; higher up branches grow out from almost every cell, most often in a secund manner (Fig. 3 a), sometimes alternating. The young branches are some- what attenuated towards their apex (Fig. 3 b) and composed of cells which are some- what longer upwards and have fewer chro- matophores. Later on the branches show a marked growing point near their base and terminate with long nearly colourless hairs (Fig. 3 a). The branches are about 15— 20/a thick, the hairs 10— lb/a. The chromatophores (Fig. 3 c, d) have the shape of short ribbons in the young cells, in the older they are small roundish discs1). Upon their upper side the branches again bear smaller ones also terminating with hairs and further plurilocular spor- Fig. 4. Ectocarpus Mit- /r,. o \ rr-,1 i i i chellæ Harv. angia (Fig. 3 a). These are developed Base of a plant successively upwards from the growing (About 100:1). point in perfect accordance with those in Ectocarpus virescens as pointed out by Sauvageau3). The pluri- locular sporangia are sessile, lanceolate cylindrical, with obtuse ') Comp. Sauvageau, C, Sur l'Ectocarpus virescens Thuret, (Journal de Bot., T. X, 1896, p. 101, fig. 2 B, C). -) Sauvageau, 1. c, p. 101, fig. 2 Please note
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