Chap. IV. CUCUEBITACiE^ 131 



a grain in weight caused a temporary flexure. The 

 lower paxt was repeatedly rubbed rather roughly, but 

 no curvature ensued ; yet this part is sensitive to pro- 

 longed pressure, for when it came into contact with a 

 stick, it would slowly wind round it. 



One of my plants bore two shoots near together, 

 and the tendrils were repeatedly drawn across one 

 another, but it is a singular fact that they did not 

 once catch each other. It would appear as if they had 

 become habituated to contact of this kind, for the 

 pressure thus caused must have been much greater 

 than that caused by a loop of soft thread weighing 

 only the one-sixteenth of a grain. I have, however, 

 seen several tendrUs of Bryonia dioiea interlocked, but 

 they subsequently released one another. The tendrils 

 of the Echinocystis are also habituated to drops of 

 water or to rain ; for artificial rain made by violently 

 flirtiQg a wet brush over them produced not the least 

 effect. 



The revolving movement of a tendril is not stopped 

 by the curving of its extremity after it has been 

 touched. When one of the lateral branches has firmly 

 clasped an object, the middle branch continues to 

 revolve. When a stem is bent down and secured, so 

 that the tendril depends but is left feee to move, its pre- 

 vious Tevolving movement is nearly or quite stopped ; 

 but it soon begins to bend upwards, and as soon as it 

 has become horizontal the revolving movement recom- 

 mences. I tried this four times ; the tendril generally 

 rose to a horizontal position in an hour or an hour and 



