86 



MB. DABWIN ON CLIMBING PLANTS. 



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 bocomes 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 



Fig. 11. 



Ampelopsis hederacea 



A. Tendril, with the young loaf. 



B. Tendril, several weeks after its attaelnnent 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 



