. The power of movement in plants . Plants; Botany. 52 CIECUMNUTATION OF SEEDLINGS. Chap. 1 Fig. morning, before it was light, they had risen to 59° above the horizon; in the afternoon of the same day they were found again horizontal. Beta vulgaris (Chenopodese).—The seedlings are excessively sensitive to light, so that although on the first day they were uncovered only during two or three minutes at each observation, they all moved steadily towards the side of the room whence the light proceeded, and the trac- ings consisted only of slightly zigzag lines directed towards the light. On th
. The power of movement in plants . Plants; Botany. 52 CIECUMNUTATION OF SEEDLINGS. Chap. 1 Fig. morning, before it was light, they had risen to 59° above the horizon; in the afternoon of the same day they were found again horizontal. Beta vulgaris (Chenopodese).—The seedlings are excessively sensitive to light, so that although on the first day they were uncovered only during two or three minutes at each observation, they all moved steadily towards the side of the room whence the light proceeded, and the trac- ings consisted only of slightly zigzag lines directed towards the light. On the next day the plants were placed in a completely darkeued room, and at each observation were illuminated as much as possible from vertically above by. a small wax taper. The annexed figure (Fig. 39) shows the move- ment of the hypocotyl during 9 h. under these circumstances. A second seedling was similarly observed at the same time, and the tracing had the same peculiar character, due to the hypocotyl often mov- ing and returning in nearly parallel lines. The movement of a third hypocotyl differed greatly. We endeavoured to trace the movements of the cotyledons, and for this purpose some seedlings were kept in the dark, but they moved in an abnormal manner; they continued rising from to 2 , then moved laterally, and from 3 to 6 descended; whereas cotyledons which have been exposed all the day to the light rise in the evening so as to stand verti- cally at night; but this statement applies only to young seedlings. For instance, six seedlings in the greenhouse had their cotyledons partially open for the first time on the morning of November 15th, and at all were completely closed, so that they might properly be said to be asleep. Again, on the morning of November 27th, the cotyledons of four other seedlings, which were surrounded by a collar of brown paper so that they received light only from above, were open to the extent of 89°; at 10 the
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Keywords: ., bookcentury1800, booksubjectbotany, booksubjectplants, bookyear18
