130 TENDEIL-BEAEEES. Chap. IV. 



arrested. As soon as the tendril with its three 

 branches begins to stiffen itself in this manner and to 

 rise from an inclined into a vertical position, the 

 reTolving motion becomes more rapid ; and as soon 

 as the tendril has succeeded in passing over the ex- 

 tremity of the shoot or point of difficulty, its motion, 

 coinciding with that from its weight, often causes it to 

 fall into its previously inclined position so quickly, 

 that the apex could be seen travelling like the minute 

 hand of a gigantic clock. 



The tendrils are thin, from 7 to 9 inches in length, 

 with a pair of short lateral branches rising not far 

 from the base. The tip is slightly and permanently 

 curved, so as to act to a limited extent as a hook. The 

 concave side of the tip is highly sensitive to a touch ; 

 but not so the convex side, as was likewise observed 

 to be the case with other species of the family by 

 Mohl (p. 65). I repeatedly proved this diiSference by 

 lightly rubbing four or five times the convex side of 

 one tendril, and only once or twice the concave side 

 of another tendril, and the latter alone curled inwards. 

 In a few hours afterwards, when the tendrils which 

 had been rubbed on the concave side had straightened 

 themselves, I reversed the process of rubbing, and 

 always with the same result. After touching the 

 concave side, the tip becomes sensibly curved in one or 

 two minutes ; and subsequently, if the touch has been at 

 all rough, it coils itseK into a helix. But the helix 

 will, after a time, straighten itseK, and be again ready 

 to act. A loop of thin thread only one-sixteenth of 



