. Fresh-water biology. Freshwater biology. iS8 PRESH-WATER BIOLOGY 173 (171, 172) 171 (172, 173) Cells single, attached; oval, cylindrical, fusifonn, or curved in shape. Chromatophore single and parietal. Characium A. Braun. Cells oval, pointed, or rounded at the ends, straight or curved, sessile or stalked; attached to a substratum with or without a disc. A pyrenoid usually present. Reproduction by zoospores which have two dUa, a pyrenoid, and a pigment spot. Characium is very common on filamentous algae in all localities. The shape is greatly influenced by the direction of the rays of light.
. Fresh-water biology. Freshwater biology. iS8 PRESH-WATER BIOLOGY 173 (171, 172) 171 (172, 173) Cells single, attached; oval, cylindrical, fusifonn, or curved in shape. Chromatophore single and parietal. Characium A. Braun. Cells oval, pointed, or rounded at the ends, straight or curved, sessile or stalked; attached to a substratum with or without a disc. A pyrenoid usually present. Reproduction by zoospores which have two dUa, a pyrenoid, and a pigment spot. Characium is very common on filamentous algae in all localities. The shape is greatly influenced by the direction of the rays of light. Fig. 197. Characium loniipes Rabenhorst. X 600. (Original.) 172 (171, 173) Cells as in Characium, but the chlorophyll in many small, parietal discs Characiopsis Borzi. The color is pale green. The zoospores are liberated by the wall of the upper portion of the cell becoming dissolved. According to West, aplano- spores may be formed, each of which becomes a gametangium and pro- duces two or four gametes. Characiopsis is less frequent than Characium but is found under the same conditions. Fig. 198. Characiopsis sp. X 600. (Original.) Cells attached, the new generation clustered at the free tip of the empty mother cell Sciadium A. Braun. Thallus of six to eight cylindrical cells, radiating from the tip of a sessile, empty, cylindrical membrane; reproduction by six to eight zoospores with two cilia each, which attach themselves at the tip of the mother-membrane after the removal of a cap which liberates the spores. Lemmermann unites Sciadium with Ophiocytium because rarely in Ophiocytium the new generation develops from one end of the parent cell, but the sessile characteristic and the basal disc of Sciadium would seem to separate it from Ophiocytium where these characteris- tics are not found. Fig. 199. Sciadium arbuscula A. Braun. X 600. (After Rabenhorst.) Reproduction by fission and by zoospores. Family Chlorosphaeraceae. Only one genus known Chlorosphaera Klebs. Cells usually
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
