. Plants; a text-book of botany. Botany. ROOTS. 91 absorb moisture from them. By these root hairs the absorb- ing surface, and hence the amount of absorption, is greatly increased. Individual root hairs do not last very long, but new ones are constantly ap- pearing just behind the advancing root tips, and the old ones are as constantly disap- pearing. (1) Oeot7-opism and 'hydrotropism. — Many outside influences afPect roots in the direction of their growth, and as soil roots are espe- cially favorable for ob- serving these influ-. FiG. 85. Apparatus to show the influence of water (hydrotropism
. Plants; a text-book of botany. Botany. ROOTS. 91 absorb moisture from them. By these root hairs the absorb- ing surface, and hence the amount of absorption, is greatly increased. Individual root hairs do not last very long, but new ones are constantly ap- pearing just behind the advancing root tips, and the old ones are as constantly disap- pearing. (1) Oeot7-opism and 'hydrotropism. — Many outside influences afPect roots in the direction of their growth, and as soil roots are espe- cially favorable for ob- serving these influ-. FiG. 85. Apparatus to show the influence of water (hydrotropism) upon the direction of roots. The ends (a) of the box have hooks for hanging, while the box proper is a qylinder or trough of wire netting and is filled with damp sawdust. In the sawdust arc planted peas (g-), whose roots (/i, i, k, m) first descend until they emerge from the damp sawdust, but soon turn back toward it.—After Sachs. ences, two prominent ones may be mentioned. The influence of gravity, or the earth influence, is very strong in directing the soil 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 Coulter, John Merle, 1851-1928. New York, D. Appleton and company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1900
