. Botany; an elementary text for schools. Plants. A LGiE 179. be used. Tlie thread is divided into long cells by cross-walls wbieh, according to the species, are either straight or curiously fokled (Fig. 314). The chlorophyll is arranged in beautiful spiral bands near the wall of each cell. From the character of these bands the phint takes its name. Each cell is provided with a nucleus and other protoplasm. The nucleus is suspended near the center of the cell, a. Fig. 313, by delicate strands of protoplasm radiating toward the wall and terminat- ing at certain points in the chlorophyll band. T
. Botany; an elementary text for schools. Plants. A LGiE 179. be used. Tlie thread is divided into long cells by cross-walls wbieh, according to the species, are either straight or curiously fokled (Fig. 314). The chlorophyll is arranged in beautiful spiral bands near the wall of each cell. From the character of these bands the phint takes its name. Each cell is provided with a nucleus and other protoplasm. The nucleus is suspended near the center of the cell, a. Fig. 313, by delicate strands of protoplasm radiating toward the wall and terminat- ing at certain points in the chlorophyll band. The remainder of the protoplasm forms a thin layer lining the wall. The interior of the cell is filled with cell-sap. The protoplasm and nucleus cannot be easily seen, but if the plant is stained with a dilute alcoholic solution of eosin (146) they become clear. Spirogyra is propagated vegetatively by the break- ing off of parts of the threads, which continue to grow as new plants. Resting-spores, which may remain dormant for a time, are formed by a process known as cunjugation. Two threads lying side by side send out short projections, usually from all the celis of a long series (Fig. 314). The projections or processes from opposite cells grow toward each other, meet and fuse, forming a connecting tube between the cells. The protoplasm, nucleus, and chlorophyll band of one cell now pass througli this tube, and unite with the contents of the other cell. The entire mass then becomes surrounded by a thick cellulose wall, thus completing the resting-spore, or zygospore (Fig. 314, s). Vancheria is another alga common in shallow water and on damp soil. The tliallus is much branclied, but the threads are not divided by cross-walls as in spirogyra. The plants are attached by means of colorless root-like organs which are much like the root-hairs of the higher plants: these are rhizoids. The chlorophyll is in the form of grains scattered through the thread. Vaucheria has a special mode o
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