Chap. IV. CUCURBIT ACEM. 133 



there had been no sensible increase of length within 

 the time. When a stick, flat on one side, was 

 similarly placed, the tip of the tendril could not 

 curl beyond the flat surface, but coiled itself into 

 a helix, which, turning to one side, lay flat on the 

 little flat surface of wood. In one instance a portion 

 of tendril three-quarters of an inch in length was thus 

 dragged on to the flat surface by the coiling in of the 

 helix. But the tendril thus acquires a very insecure 

 hold, and generally after a time slips off. In one case 

 alone the helix subsequently uncoiled itself, and the 

 tip then passed round and clasped the stick. The 

 formation of the helix on the flat side of the stick 

 apparently shows us that the continued striving of the 

 tip to curl itself closely inwards gives the force which 

 drags the tendril round a smooth cylindrical stick. 

 In this latter case, whilst the tendril was slowly and 

 quite insensibly crawling onwards, I observed several 

 times through a lens that the whole surface was not in 

 close contact with the stick ; and I can understand the 

 onward progress only by supposing that the movement 

 is slightly undulatory or vermicular, and that the tip 

 alternately straightens itself a little and then again 

 curls inwards. It thus drags itself onwards by an 

 insensibly slow, alternate movement, which may be 

 compared to that of a strong man suspended by the 

 ends of his fingers to a horizontal pole, who works his 

 fingers onwards until he can grasp the pole with the 

 palm of his hand. However this may be, the fact is 

 certain that a tendril which has caught a round stick 



