Page:Darwin - On the movements and habits of climbing plants.djvu/61

 quite still for 12 h. or 18 h., and then recommence revolving; such strongly marked interruptions in the movements I have observed in no other plant.

The leaves bear four leaflets, themselves subdivided, and terminate in a much-branched tendril. The main petiole of the leaf, whilst young, moves spontaneously by curving itself, and follows nearly the same irregular course, and at about the same rate, with the internodes. The movement to and from the stem is naturally the most conspicuous, and I have seen the chord of the curved petiole forming an angle of 59° with the stem, and an hour afterwards an angle of 106°. The two opposite petioles do not move together, and one is sometimes raised so much as to stand close to the stem whilst the other is not far from horizontal. The basal part of the petiole moves less than the distal part. The tendrils, besides being carried by the moving petioles and internodes, themselves move spontaneously, and the opposite tendrils occasionally move in opposite directions. By these several movements of the young internodes, of the petioles, and of the tendrils, all acting together, a wider space is swept for a support.

In young plants, the tendrils are about three inches in length: they bear two lateral and two terminal branches; and each branch bifurcates twice, with the tips forming blunt double hooks, having both points directed to the same side. All the branches are sensitive on all sides; and after being lightly rubbed, or after coming into contact with a stick, they bend in about 10 m. One that became, after a light rub, curved in 10 m., continued bending for between 3 h. and 4h., but subsequently in 8 h. or 9 h. became straight again. Tendrils, which have caught nothing, ultimately contract into an irregular spire, as they do also, only much more quickly, after clasping a support. In both cases the petiole bearing the leaflets, which at first is straight and inclined a little upwards, moves downwards and abruptly bends itself in the middle into a right angle; but this is more plainly seen in E. miniatus than in E. scaber. The action of the tendrils in the Eccremocarpus is in some respects analogous to that of the tendrils of Bignonia capreolata; but the whole tendril does not move from the light, nor do the hooked tips become enlarged into cellular disks. After the tendrils have come into contact with moderately thick cylindrical sticks or with rugged bark, the several branches may be observed slowly to lift themselves up, change their position, and again come into contact with them. The object of these