. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. 366 THE NON-VASCULAR PLANTS ferentiation of cells begins among the many-celled algae and this means differentiation of function. Ulothrix, a form not uncommon in brooks, shows very well this differentiation of cells. (See Figure 164.) You note that the lowest cell, which is quite dif- ferent from the others, serves as an anchor. Other cells serve espe- cially in reproduc- tion. Any single cell which repro- duces without fusion with another cell is called a
. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. 366 THE NON-VASCULAR PLANTS ferentiation of cells begins among the many-celled algae and this means differentiation of function. Ulothrix, a form not uncommon in brooks, shows very well this differentiation of cells. (See Figure 164.) You note that the lowest cell, which is quite dif- ferent from the others, serves as an anchor. Other cells serve espe- cially in reproduc- tion. Any single cell which repro- duces without fusion with another cell is called a spore. Multicellular algae reproduce chiefly by spores. In Ulothrix certain cells of the fila- ment, under condi- tions which favor this process, begin to divide into spores. What was a vegetative pro- toplast becomes a considerable number of spores. An opening appears in the wall, and these spores swim out. Their swimming is accomplished by the movement of their cilia (singular, cilium). A cilium is a thread-like extension of protoplasm. The spores of Ulothrix have four cilia at the top, The swimming spores of other algae have other. A Fig. 164. — Ulothrix. A, the base of a filament showing the manner of attachment, and the differentiation of the lowest cell. B, portion of a filament whose pro- toplasts have formed spores; note the two cells from which the spores have already escaped. C, portion of a filament showing zoospores of two sizes both be- fore and after their escape into the water; at the top are shown two spores each of which has resulted from the fusion of two of the smaller zoospores; these are oospores. See Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John G. (John Gaylord), b. 1876. New York, American Book Co
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
