. Foundations of botany. Botany; Botany. TYPES OF CRYPTOGAMS; THALLOPHYTES 241 in nitric acid, the cellulose wall and its contents may be destroyed and the markings of the siliceous shell more easily observed. Each diatom consists of a single cell. 272. Movements of Diatoms. — Living diatoms exhibit a peculiar power of movement. In the boat-shaped species the movement is much like that of a row-boat, forward or backward. THE STUDY OF SPIROGYRA 273. Occurrence. — Spirogyra, one of the plants commonly known as pond-scum, or «frog-spit," occurs widely distributed throughout the country in po
. Foundations of botany. Botany; Botany. TYPES OF CRYPTOGAMS; THALLOPHYTES 241 in nitric acid, the cellulose wall and its contents may be destroyed and the markings of the siliceous shell more easily observed. Each diatom consists of a single cell. 272. Movements of Diatoms. — Living diatoms exhibit a peculiar power of movement. In the boat-shaped species the movement is much like that of a row-boat, forward or backward. THE STUDY OF SPIROGYRA 273. Occurrence. — Spirogyra, one of the plants commonly known as pond-scum, or «frog-spit," occurs widely distributed throughout the country in ponds, springs, and clear streams. It is of a green or yellowish-green color, and in sunny weather usually iloats on or near the surface of the water, buoyed up by the numerous oxygen bubbles which it sets free. It may be found flourishing in unfrozen springs, even in midwinter. 274. Examination with the Magnifying Glass.^ — Float a little of the material in a white plate, using just water enough to cover the bottom of the latter. Study with the magnifying glass and note the green color of the threads and their great length as compared with their thick- ness. Are all the filaments about equal to each other in diameter ? Handle a mass of the material and describe how it feels between the fingers. 275. Examination with the Microscope. — Mount in water under a large cover-glass and examine first with a power of about 100 1 Consult Huxley's Biology and Spalding's Introduction to Fig. 176. —A Group of Diatoms. Aj Achnanthes; B,Cocconema; C, Meridian; D, 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 Bergen, Joseph Y. (Joseph Young), 1851-1917; Eastwood, Alice, 1859-1953. Boston, Ginn & Co.
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