. The power of movement in plants . Plants; Botany. CnAP. I. GITHAGO. 21 two or three minutes whilst a glass filament was fixed vertically to the hypoootyl; it was then again placed in darkness for half an hour and afterwards observed by light passing through bichromate of potassium. The point, oscillating as usual, crossed five divisions of the micrometer (i. e. -^ inch) in 1 m. 30 s. The seedling was then left in darkness for an hour, and now it required 3 m. 6 s. to cross one division, that is, 15 m. 30 s. to have crossed five divisions. Another seedling, after being occasionally observed i
. The power of movement in plants . Plants; Botany. CnAP. I. GITHAGO. 21 two or three minutes whilst a glass filament was fixed vertically to the hypoootyl; it was then again placed in darkness for half an hour and afterwards observed by light passing through bichromate of potassium. The point, oscillating as usual, crossed five divisions of the micrometer (i. e. -^ inch) in 1 m. 30 s. The seedling was then left in darkness for an hour, and now it required 3 m. 6 s. to cross one division, that is, 15 m. 30 s. to have crossed five divisions. Another seedling, after being occasionally observed in the back part of a northern room with a very dull light, and left in complete darkness for intervals of half an hour, crossed five divisions in 5 m. in the direction of the window, so that we concluded that the move- ment was heliotropic. But this was probably not the case, for it was placed close to a north-east window and left there for 25 m., after which time, instead of moving still more quickly towards the light, as might have been expected, it travelled only at the rate of 12 m. 30 s. for five divisions. It was then again left in complete darkness for Ih., and the point now travelled in the same direction as before, but at the rate of 3 m. 18 s. for five divisions. We shall have to recur to the cotyledons of the cabbage in a future chapter, when we treat of their sleep-movements. The circumnutation, also, of the leaves of fully-developed plants will hereafter be described. Fig. 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 Darwin, Charles, 1809-1882; Darwin, Francis, Sir, 1848-1925. New York : D. Appleton
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