. Botany for high schools. Botany. 232 GENERAL MORPHOLOGY OF PLANTS cells. They occur in fresh, brackish, or salt water, and on damp rocks, soil, etc. A number of species have a preference for foul water or waters which contain organic matter. Some of these on decaying produce very foul odors, and sometimes occur in reser- voirs for public water supply. Here they may become a great nuisance and a menace to health. They can be destroyed by adding small quantities of copper sulphate to the water in the reservoirs without injury to the water for drinking purposes.* Some of the blue-green algae ar
. Botany for high schools. Botany. 232 GENERAL MORPHOLOGY OF PLANTS cells. They occur in fresh, brackish, or salt water, and on damp rocks, soil, etc. A number of species have a preference for foul water or waters which contain organic matter. Some of these on decaying produce very foul odors, and sometimes occur in reser- voirs for public water supply. Here they may become a great nuisance and a menace to health. They can be destroyed by adding small quantities of copper sulphate to the water in the reservoirs without injury to the water for drinking purposes.* Some of the blue-green algae are remarkable for growing in warm, or hot, water, at a temperature which would prevent the growth of other forms of plant life except certain bacteria. In the hot water flowing from the geysers at Yellowstone Park some of these algae live in water at a temperature of 58^-68° C, or scantily at 75^-77° C. The blue-green algae multiply by division of the cells and by breaking up of the colonies or threads. In the filamentous forms this division takes place much as in spirogyra, by simple splitting or fission of the cells. For this reason they are sometimes called fission algae. See also Bacteria, Chapter XXV. Other char- acters are brought out in a study of the examxples. 374. Gloeocapsa.—This is a one-celled alga which forms thin bluish-green patches on the ground or on rocks, logs, etc. Each cell is roundish, and is surrounded by a thick capsule of a gelati- nous nature which is stratified in distinct concentric layers. The cells look as if they were enclosed in gelatinous capsules, hence the name Glceocapsa. In multiplication the cells divide into t^vo daughter cells and these again divide in like manner. The divi- sions take place in different directions, each cell having a distinct stratified gelatinous envelope, and several of these enclosed for a time in the envelope of the parent cell, which becomes larger with the increase in the number of the cells. * See Bull. Xo. 64
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