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The desmids, members of Chlorophyta, have flattened, relatively large Cells, with a characteristic bilateral symmetry (Figure 26.4). Asexual reproduction involves the systhesis of two new half-Cells in the equitorial plane, followed by cleavage between the new half-Cells to produce two bilaterally symmetrical daughters, each of which has a Cell consisting of an"old" and a "new" half.
 
The desmids, members of Chlorophyta, have flattened, relatively large Cells, with a characteristic bilateral symmetry (Figure 26.4). Asexual reproduction involves the systhesis of two new half-Cells in the equitorial plane, followed by cleavage between the new half-Cells to produce two bilaterally symmetrical daughters, each of which has a Cell consisting of an"old" and a "new" half.
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The diatoms (Figure 26.5), members of the Chrysophyta, have organic walls impregnated with silica. The architecture of the diatom wall is exceedingly complex; it always consists of two overlap
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The diatoms (Figure 26.5), members of the Chrysophyta, have organic walls impregnated with silica. The architecture of the diatom wall is exceedingly complex; it always consists of two overlapping halves,like the halves of apetri dish. Division is longitudinal , each daughter Cell retaining half of the old wall and synthesizing a new half.
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Although devoid of flagella, some desmids and diatoms can move slowly over solid substrates. The mechanism of desmid locomotion is not known. The locomotion of diatoms is accomplished by a special modification of ameboid movement. In
    
== The Natural Distribution of Algae ==
 
== The Natural Distribution of Algae ==
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