. Plant life, considered with special references to form and function. Plant physiology. THE MOVEMENTS OF PLANTS. 199 The central axis of both root and stem in the majority of plants is so, but lateral branches of both place themselves at an angle to the action of gravity, sometimes at a right angle, at other times at a highly obtuse or acute angle. That is, they are more or less perfectly transversely geotropic. What-. FlG. 195.âPart of centrifuge. «, the axle, rotated at a high speed by water or electric motor, to which is attached the circular metal plate, r, r, carr^'ing a disk of cork. k
. Plant life, considered with special references to form and function. Plant physiology. THE MOVEMENTS OF PLANTS. 199 The central axis of both root and stem in the majority of plants is so, but lateral branches of both place themselves at an angle to the action of gravity, sometimes at a right angle, at other times at a highly obtuse or acute angle. That is, they are more or less perfectly transversely geotropic. What-. FlG. 195.âPart of centrifuge. «, the axle, rotated at a high speed by water or electric motor, to which is attached the circular metal plate, r, r, carr^'ing a disk of cork. k. To the latter are attached two seedling beans. A, A, by means of pins ; st, the primary stem; //. the primary root. 0\'er the seedlings the cover, .;.â â , is placed to keep them moist. After a few hours the lateral roots have turned into the direction of tlie cen- trifugal force, which was sufficiently powerful to o\'ercome that of gravity except near of rotation, .r. One half natural size.âAfter Sachs. ever the normal position of any organ, it will be regained by the growing parts as rapidly as possible when the plant is forcibly displaced. This can only be brought about by the curvatures produced by unetjual growth of the younger parts. If a potted plant be laid upon its side for a short time and then erected before any response to the stimulus occurs its growing parts still curve to one side, although not so far as if they had been allowed to remain in the horizontal position. 289. Grasses.âIn only a few cases do the maturer parts of plants regain their power of growth under the stimulus of gravity. The basal portion of the internodes of grasses, however, remain for a long time capable of growth ; hence,. 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
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