. The power of movement in plants . Plants; Botany. Gil A p. X. APOGEOTROPISM. 501 Fig. 187. upwards, and rose during the first 3 h. 10 m. in a nearly straight line (Fig. 187); but it was not possible to trace the upward move- ment on the vertical glass for the first 1 h. 10 m., so that the nearly straight line in the diagram ought to have been much longer. During the next 11 h. the hypocotyl circum- nutated, describing irregularfigures, each of which rose a little above the one previously formed. During the night and following early morn- ing it continued to rise in a zigzag course, so that a
. The power of movement in plants . Plants; Botany. Gil A p. X. APOGEOTROPISM. 501 Fig. 187. upwards, and rose during the first 3 h. 10 m. in a nearly straight line (Fig. 187); but it was not possible to trace the upward move- ment on the vertical glass for the first 1 h. 10 m., so that the nearly straight line in the diagram ought to have been much longer. During the next 11 h. the hypocotyl circum- nutated, describing irregularfigures, each of which rose a little above the one previously formed. During the night and following early morn- ing it continued to rise in a zigzag course, so that apogeotropism was still acting. At the close of our ob- servations, after 23 h. (represented by the highest dot in the diagram) the hypocotyl was still 32° from the perpendicular. There can be little doubt that it would ulti- mately have become upright by describing an additional number of irregular ellipses, one above the other. Apoyiotivpifsm retarded by Helio- tropism. — When the stem of any plant bends during the day towards a lateral light, the fnovcment is opposed by apogeotropism; but as the light gradually wanes in the evening the latter power slowly gains the upper hand, and draws Brassica oleracea: apogeotrnpic the stem back into a vertical movement of hypocotyl, on vertical glass, from position. Here then we have a good opportunity for observing how apogeotropism acts when very nearly balanced by an opposing force. For instance, the plumule of TropcBolum majus (see former Fig. 175) moved towards the dim evening light in a slightly zigzag line until , it then returned on its course unfci). Sept. 12th to 13th. The upper part of the figure is more magnified than the lower part. If the whole course had been traced, the straight upi'ight line wouM have been much longer. P''igure here reduced to one-third oi the oi'igiual Please note that these images are extracted from scanned page images that may have been digitally enhanced
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Keywords: ., bookcentury1800, bookdecade, booksubjectbotany, booksubjectplants
