. Fresh-water biology. Freshwater biology. THE FRESH-WATER ALGAE 173 Leaflets and internodes of both axis and leaf are each of but a single cell, the walls of which are lined with chloroplasts and in the center of which is a large sap cavity. In Chara the internodal cell is more or less completely covered by a layer of cortical cells of the same structure. A swamp-like odor is usually present. Reproduction sexual only; plants either dioecious or monoecious, but in the latter case the antheridia mature before the oogonia. The antheridium is spherical, its wall composed of eight "shields&qu
. Fresh-water biology. Freshwater biology. THE FRESH-WATER ALGAE 173 Leaflets and internodes of both axis and leaf are each of but a single cell, the walls of which are lined with chloroplasts and in the center of which is a large sap cavity. In Chara the internodal cell is more or less completely covered by a layer of cortical cells of the same structure. A swamp-like odor is usually present. Reproduction sexual only; plants either dioecious or monoecious, but in the latter case the antheridia mature before the oogonia. The antheridium is spherical, its wall composed of eight "shields" which contain red chromo- plasts on their inner surfaces. Attached to the middle of each shield and pro- jecting inward is a club-shaped cell, the manubrium, which in turn bears a short cell, the capitulum. To the capitula are attached secondary capitula bearing four long, slender filaments made up of many cells, each containing an antherozoid; the antherozoids are spiral in form and have two cUia at their anterior ends; the oogonia are egg-shaped and are covered by five spiral cells, the tips of which are divided, once in Chara and twice in Niiella, to form the "; The term sporophydium has been suggested for the structure including the oospore, its basal cell, and enveloping cells. Below the crown cells the antherozoids penetrate to effect fertilization. Oospores are brown or yellowish; on germination they produce first a simple row of cells, the pro- embryo, on which the new individual arises. 254 (257) Points of the crown of the oogoniimi two-celled. S.'Vfamily Nitelleae . 255 255 (256) Leaflets projecting beyond the tips of the leaves, giving the appear- ance of forked leaves Nitella Agardh. Axis and leaves never with a cortical covering and seldom encrusted with lime. Leaves with but one whorl of leaflets, but these in turn may bear whorls of leaflets, those of the last order always projecting beyond the leaves, giving them a divided appearance. The ant
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
