. Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University. Botany; Botany. 172 CBYPTOGAMS Sphere. Its only known mode of reproduction is by division. That is, eacli individual divides by a cross wall, and the two new individuals so produced increase in size. Before they separate they may each again divide ; and ill fact the plants are commonly found cohering in small colonies (Fig. 284, B). 416. Ulothrix. — The fine unbranched filaments of Ulo- thrix are abundant in fresh water, wdi
. Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University. Botany; Botany. 172 CBYPTOGAMS Sphere. Its only known mode of reproduction is by division. That is, eacli individual divides by a cross wall, and the two new individuals so produced increase in size. Before they separate they may each again divide ; and ill fact the plants are commonly found cohering in small colonies (Fig. 284, B). 416. Ulothrix. — The fine unbranched filaments of Ulo- thrix are abundant in fresh water, wdiere they grow attached to stones, sticks, etc. (Fig. 285, a). The fila- ments increase in length by the division and elongation of any or all of the cells. When Ulothrix is about to repro- duce, its cells divide internally, so that within each one are produced several cells ; but the latter liave )io cell wall formed about them. When these naked cells escape, by the rupture ¥0,^ of the mother cell waW, it is seen that they are. 2S5. Ulothrix: o, a young filament: b, larger zoospore; c. escape of these spi>res; J, e, escape and conjugatiou of smaller zoospores. — provided with hairlike organs called cilia, by means of which they swim energetically about (Fig. , /), (7). The motile cells Tcalled, from their animal-like power of locomotion, zooqjores) are of two kinds, large and sm:ill. The larger have four cilia (Fig. 285, h). After a short active period they settle down, lose their cilia, invest themselves with cell walls, and germinate In' growing out into new filaiuents. The smaller zoospores are provided M'ith but two cilia. After swarming they fuse (Fig. 285, c), generall}' in pairs. This process, wherein two cells unite to form the germ of a new plant, is called coiijufii'ition. The body formed Ijy tlie conjuga- tion of two similitr cells is a zi/i/osjiore. In tlie case of. Please note that these images are extracted from scanned page images that may
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