. Dansk botanisk arkiv. Plants; Plants -- Denmark. F. Børgesen: Rhodophyceæ of the Danish W. Indies. 201 This beautifully purple-rose plant was found upon the pikes of Eiicidaris tribuloides, often covering these quite densely ; the tufts reach a height of ^h cm. The basal creeping filaments (Figs. 189, 190 A) are irregularly branched; they are about 30,« broad, having a very thick wall (often 8—10// thick). The filaments are fastened to the pikes of the Echinoderm by means of rhizoids. These are shorter or longer without any transverse walls, but having very thick peripheral walls, the lumen
. Dansk botanisk arkiv. Plants; Plants -- Denmark. F. Børgesen: Rhodophyceæ of the Danish W. Indies. 201 This beautifully purple-rose plant was found upon the pikes of Eiicidaris tribuloides, often covering these quite densely ; the tufts reach a height of ^h cm. The basal creeping filaments (Figs. 189, 190 A) are irregularly branched; they are about 30,« broad, having a very thick wall (often 8—10// thick). The filaments are fastened to the pikes of the Echinoderm by means of rhizoids. These are shorter or longer without any transverse walls, but having very thick peripheral walls, the lumen of the cells is, in this way, reduced to very little. At the bottom end the rhizoids for the most part broaden out to a flat, roundish, irregularly lobed disc. The erect filaments are very straight and not much branched; the branches issue alternatingly, but seldom oppositely. The filaments are from 16—25// broad; the cells from 3—5 times as long as the diameter. The last mentioned contain many small, oblong, parietal chromato- phores more or less growing together, forming irregularly lobed, parietal plates and having several nuclei especially in the apical cell where often more than ten are to be found. Only plants with tetra- sporangia were found. These are situated terminally upon a short one-celled branchlet growing out singly (very rarely in twos) from the upper end of the mother-cell (Fig. 190 C). Only seldom the branchlet may have two cells; sometimes, too, it has a lateral sfcalk-cell with a sporangium (Fig. 190 B). The sporangia are tetrahedrally divided, ovate roundish, about 46—52/i long, and 44—46/7. broad; the wall of the sporangia is very thick, 6—8/^ or Fig. 190. Spermothamnion investiens (Crouan) Vickers, var. cidaricola Borgs. A, piece of a plant with creeping and erect filaments (25:1); 5 and C, pieces of erect fila- ments with tetraspores {B, 50:1; C, 70:1). The original specimens upon which the brothers Crouan have based the description
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Keywords: ., bookcentury1900, bookcollectio, bookdecade1910, booksubjectplants
