. Outlines of plant life : with special reference to form and function . Botany. Fig. 6.—Nostoc, ^, a'gelatinous colony, irregularly lobed. Natural size. .5, a por- tion of a serpentine filament with five heterocysts (one at each end by which it was separated from the rest of the cells composing the filament, and three intermediate ones) and the jelly belonging to it. Magnified about 400 diam.—After Thuret and Janczewski. real independence of the cells, even though they remain con- nected, is shown by the fact that such a chain may be broken up into any number of pieces and each piece will ret
. Outlines of plant life : with special reference to form and function . Botany. Fig. 6.—Nostoc, ^, a'gelatinous colony, irregularly lobed. Natural size. .5, a por- tion of a serpentine filament with five heterocysts (one at each end by which it was separated from the rest of the cells composing the filament, and three intermediate ones) and the jelly belonging to it. Magnified about 400 diam.—After Thuret and Janczewski. real independence of the cells, even though they remain con- nected, is shown by the fact that such a chain may be broken up into any number of pieces and each piece will retain all its powers. Here and there in the chain there occur cells unlike the rest, whose purpose seems to be to break the chain into pieces, which work their way out of the jelly and grow into independent colonies. The association of considerable numbers of these plants in colonies gives rise to masses of jelly which vary from the size of a pin-head to 2-5 centimeters in diameter. They may be found adhering to water-weeds as clear- or dirty-green masses, or sometimes floating free {A, fig. 6). EXERCISE I. Nostoc or Bivularia.—i. Observe the size and form of the colonies and the consistence of the jelly enclosing them. (^11.). 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 Barnes, Charles Reid, 1858-1910. New York : Henry Holt and Company
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