. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . of the colony (fig. 114). In Palmophyllum division of the GloeocystesR 189 cells is in two directions in a plane such that the colony becomes a flatexpansion. The majority of the divisions are in one direction and the cellsin consequence assume a seriate arrangement. The chloroplast is parietaland massive, with or without a pyrenoid. The only genera are: Palmophi/Hitm Kiitzing, 1845; Collinsiella Sctchell & Gardner,1903. Both are freshwater g
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . of the colony (fig. 114). In Palmophyllum division of the GloeocystesR 189 cells is in two directions in a plane such that the colony becomes a flatexpansion. The majority of the divisions are in one direction and the cellsin consequence assume a seriate arrangement. The chloroplast is parietaland massive, with or without a pyrenoid. The only genera are: Palmophi/Hitm Kiitzing, 1845; Collinsiella Sctchell & Gardner,1903. Both are freshwater genera attached to sul nnerged stones. Sub-family GUEOCYSTE/E. In this sub-family the plants consist of smallcolonies of cells each of which is surrounded by a lamellose mucous invest-ment. The concentric coats of mucus can be distinguished either roundeach individual cell or round a small group of daughter-cells. The greatestlamellation of the enveloping jelly is seen in Asterococcus, in which theenvelope round a single cell (25—30 /n in diameter) may attain a diameterof 180/n. In Palmodictyon (fig. 1155) the groups of cells with their sur-. Fig. 115. A, four-celled colony of Glaiotfenium Loitlesbergerianum Haiisg., x 430, showing blackdeposit in mucilaginous envelope. B, a small portion of a branched colony of Palmodictyonviride Kutz., x 430. C, colony of Hormotila tropica G. S. West, x 430. rounding integuments are disposed in more or less cylindrical threads whichbranch and anastomose with each other; and in Hormotila the cells areusually aggregated to form a thin stratum, the secretion of mucus beingmostly on one side so that each cell becomes possessed of a lamellate mucousstalk (fig. 115 C). The chloroplast is in most cases parietal and massive, with or without apyrenoid; but in Asterococcus (Scherffel, 08 A) there is an axile chloroplastwith numerous radiating outgrowths, each of which becomes slightly ex-panded against the inner side of the cell-wall. There is a
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