TWINERS AND CLIMBERS. 



205 



is caught the hook remains open and sensitive for 

 some time, but ultimately the extremity slowly curls 

 inwards and forms a coil at the end of the leaf. In 

 one leaf the hook remained open for thirty-three 

 days. When the tip has curled into the form of a 



Fig. 29. — Climbing Corydalis [Corydalis claviculata). 

 ring all sensibility is lost, but as long as it remains 

 open some sensibility is retained.^ 



We now pass on to tendril-bearers, premising that 

 tendrils are in most cases modifications of leaves 



' Darwin, " Movements of Climbing Plants," p. 79. 



