Page:Darwin - On the movements and habits of climbing plants.djvu/87

contract spirally; and in course of a week or two shrinks into the finest thread, withers and drops off. An attached tendril, on the other hand, contracts spirally, and thus becomes highly elastic; so that when the main foot-stalk is pulled, the strain is equally distributed to all the attached disks. For a few days after the Ampelopsis hederaceaA. Tendril, with the young leaf.
B. Tendril, several weeks after its attachent to a wall, with the branches thickened and spirally contracted, and with the extremities developed into disks. The unattached branches have withered and dropped off.attachment of the disks, the tendril remains weak and brittle, but it rapidly increases in thickness and acquires great strength: during the following winter it ceases to live, but remains firmly attached to the stem and to the surface of attachment. In the