. Fresh-water biology. Freshwater biology. i6o FRESH-WATER BIOLOGY. 185 (183, 184) Cells four together, never forming larger plates. From two to five spines on the external margin of each cell. Tetrastmm Chodat. Schmidle regards those forms with spines simply as different species of Slaurogenia. 186 (182, 177) Cells tour, lying in two planes Tetradesmus Smith. This coenobium resembles a Scenedesmus rolled up, and in the size, shape, and structure of the cells they are the same. : 婉 -/.'%' Fig. 207. Tetradesmus msconsiensis Smith. X 1500. (After Smith.) 187 (176) Coenobium a coarse net or a c
. Fresh-water biology. Freshwater biology. i6o FRESH-WATER BIOLOGY. 185 (183, 184) Cells four together, never forming larger plates. From two to five spines on the external margin of each cell. Tetrastmm Chodat. Schmidle regards those forms with spines simply as different species of Slaurogenia. 186 (182, 177) Cells tour, lying in two planes Tetradesmus Smith. This coenobium resembles a Scenedesmus rolled up, and in the size, shape, and structure of the cells they are the same. : 婉 -/.'%' Fig. 207. Tetradesmus msconsiensis Smith. X 1500. (After Smith.) 187 (176) Coenobium a coarse net or a concentrically-arranged circular disc of cells, formed by the joining together of zoospores while within the mother-membrane, or still within the Hberated iimer Uning of the same. Family Hydrodictyaceae . i88 188 (189) Coenobium a free-swimming circular plate of cells, one layer in thickness Pediastrum Meyen. The cells arranged either with intercellular spaces or not; marginal cells with one or two pointed projections; inner cells angled or concave; chromatophore parietal, with one pyrenoid, and perforated at one side. Reproduction by means of zoospores which are cast out together with the inner lining of the mother-membrane, and within which they form a new coenobium. An alga which greatly resembles a two-celled Pediastrum was formerly described as Euastrum by Schmidle, but Lagerheim places it in a new genus Euastropsis. The mode of reproduction is the same as for Pedi- astrum; the zoospores, however, arrange themselves in pairs instead of in a single plate, and form a number of new individuals which are set free while within the inner layer of the mother-membrane. Fig. 208. Pediastrum boryanum Meneghini. X 600. (Original.) 189 (188) Coenobium a coarse net. ... .... Hydrodictyon Roth. Nets large, each mesh bounded by five or six cylindrical cells; the chromatophore reticulate, parietal, with numerous pyrenoids; asexual re- production by zoospores, those from each cell formin
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
