. The power of movement in plants . Plants; Botany. 330 MODIFIED CIECUMNUTATION. Chap. Vn Averrhoa hilimhi (Oxalidae).—It has long been known,* firstly that the leaflets in this genus sleep; secondly, that they move spontaneously during the day; and thirdly, that they are sensi- tive to a touch; but in none cf these respects do they diffei essentially from the species of Oxalis. They differ, however, as Mr. E. I. Lynch f has lately shown, in thoir spontaneous move- ments being strongly marked. In the case of A. bilimbi, it is a wonderful spectacle to behold on a warm sunny day the leaflets one
. The power of movement in plants . Plants; Botany. 330 MODIFIED CIECUMNUTATION. Chap. Vn Averrhoa hilimhi (Oxalidae).—It has long been known,* firstly that the leaflets in this genus sleep; secondly, that they move spontaneously during the day; and thirdly, that they are sensi- tive to a touch; but in none cf these respects do they diffei essentially from the species of Oxalis. They differ, however, as Mr. E. I. Lynch f has lately shown, in thoir spontaneous move- ments being strongly marked. In the case of A. bilimbi, it is a wonderful spectacle to behold on a warm sunny day the leaflets one after the other sinking rapidly downwards, and again ascending slowly. Their movements rival those of Desmodium qyrans. At night the leaflets hang vertically down; and now Fig. Arerrhoi bilimbi: leaf asleep; drawing reduced. they are motionless, but this may be due to the opposite ones being pressed together (Fig. 132). The main petiole is in con- stant movement during the day, but no careful observations were made on it. The following diagrams are graphic representa- tions of the variations in the angle, which a given leaflet makes with the vertical. The observations were made as follows. The plant growing in a pot was kept in a high temperature, the petiole of the leaf to be observed pointing straight at the observer, being separated from him by a vertical pane of glass. The petiole was secured so that the basal joint, or pul- vinus, of one of the lateral leaflets was at the centre of a gradu- ated arc placed close behind the leaflet. A fine glass filament was fixed to the leaf, so as to project like a continuation of the ? Dr. Bruce, 'Philosophical Trans.,' 1785, p. 356. 'Journal Linn. Soo.,' vol. xvi. 1877, p. 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; Darw
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Keywords: ., bookcentury1800, booksubjectbotany, booksubjectplants, bookyear18
