. A text-book of botany for secondary schools. Botany. GERMINATION OP SEEDS 91 To the inward sloping surface is pinned a seedling whose root has well started. The photograph (Fig. 84) shows that the root, con- tinuing to grow, has turned from the ver- tical direction under the stimulus of the moisture in the bibu- lous paper, and is pursuing a general di- rection that is a re- sultant between the two stimuli. A more detailed observation of such an experi- ment shows that the root - tip sometimes turns toward and sometimes away from the moist paper. 54. Escape of the cotyledons and the pliunule
. A text-book of botany for secondary schools. Botany. GERMINATION OP SEEDS 91 To the inward sloping surface is pinned a seedling whose root has well started. The photograph (Fig. 84) shows that the root, con- tinuing to grow, has turned from the ver- tical direction under the stimulus of the moisture in the bibu- lous paper, and is pursuing a general di- rection that is a re- sultant between the two stimuli. A more detailed observation of such an experi- ment shows that the root - tip sometimes turns toward and sometimes away from the moist paper. 54. Escape of the cotyledons and the pliunule.—After the root with its branches has anchored the plantlet to the soil, the hypocotyl begins to elongate rapidly; and since the cotyledons are still within the testa this elongation results in the development of an arch, the hypocotyl arch (Fig. 85). As the arch constantly seeks to straighten itself, the upward pull on the cotyledons finally draws them out of the testa and the hypocotyl straightens. The cotyledons, however, have done their work, and although they may become green and persist for some time, in the bean they are of no further importance. It is the escape of the. Fig. 84.—A bean seedling showing the response of the root when the stimulus of gravity is from one direction and that of moisture from 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
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1906
