Chap. III. POLEMONIACEffi. 109 



time. In a plant placed in the hot-house and grow- 

 ing Tigoroiisly, a tendril revolved for not longer than 

 36 hours, counting from the period when it first became 

 sensitive ; but during this period it probably made at 

 least 27 revolutions. 



When a revolving tendril strikes against a stick, 

 the branches quickly bend round and clasp it. The 

 little hooks here play an important part, as they 

 prevent the branches from being dragged away by the 

 rapid revolving movement, before they have had time 

 to clasp the stick securely. This is especially the case 

 when only the extremity of a branch has caught 

 hold of a support. As soon as a tendril has bent 

 round a smooth stick or a thick rugged post, or has 

 come into contact with planed wood (for it can adhere 

 temporarily even to so smooth a surface as this), the 

 same peculiar movements may be observed as those 

 described under Bignonia capreolata and Eecremoear- 

 pus. The branches repeatedly lift themselves up and 

 down ; those which have their hooks already directed 

 downwards remaining in this position and securing 

 the tendril, whilst the others twist about until they 

 succeed in arranging themselves in conformity with 

 every irregularity of the surface, and in bringing 

 their hooks into contact with the wood. The use of 

 the hooks was well shown by giving the tendrils 

 tubes and slips of glass to catch; for these, though 

 temporarily seized, were invariably lost, either during 

 the re-arrangement of the branches or ultimately when 

 spiral contraction ensued. 



