. Botany, an elementary text for schools. Botany. AL G^ 179. be used. The thread is divided into long cells by cross-walls wliich, according to the species, are either straight or curiously folded (Fig. 314). The chlorophyll is arranged in beautiful spiral bands near the wall of each cell. From the character of these bands the plant 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 tlie wall and terminat- ing at certain points in the eiilorophyll band.
. Botany, an elementary text for schools. Botany. AL G^ 179. be used. The thread is divided into long cells by cross-walls wliich, according to the species, are either straight or curiously folded (Fig. 314). The chlorophyll is arranged in beautiful spiral bands near the wall of each cell. From the character of these bands the plant 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 tlie wall and terminat- ing at certain points in the eiilorophyll 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 niu-lciis caiiiidt be easily seen, but if the plant is stained with a dilute alcoholic solution of eosin (146) they become clear. Spirogyrais propagated vegetatively by the break- ing off of parts of the threads, which continue to grow as new jjlants. Resting-spores, which may remain dormant for a time, are formed by a process known as conjugation. Two threads lying side by side send out short projections, usually from all the cells 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. Tho protoplasm, nucleus, and chlorophyll band of one cell now pass through this tube, and unite with tho contents of the otiu-r cell. The entire mass then becomes surrounded by a tliick celluloso wall, thus completing tho rcsliny-spore, or ci/i/ospore (Fig. 314, r), V((u<-lirria is another alga common in shalhiw water and on damp soil. Tho thallus is much branclie<l, Imt the threads are not divideil by cross-walls as in spirogyra. Tho pliinis are attached by means of colorless root-like organs which are much like the root-hairs of the higher plants: these are rlii:<ii<ts. The clilnroiiliv II is in the roini of grains scattered through tho threa
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Keywords: ., bookauthorbai, bookcentury1900, bookdecade1900, booksubjectbotany
