Cuap. IV. CUCURBITACER. 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 
