Chap. IV- VITACE^J. 145 



movement, but turn, as was long ago observed by 

 Andrew Knight,* from the light to the dark. I have 

 seen several tendrils move in less than 24 hours, through 

 an angle of 180 to the dark side of a case in which 

 a plant was placed, but the movement is sometimes 

 much slower. The several lateral branches often move 

 independently of one another, and sometimes irregu- 

 larly, without any apparent cause. These tendrils are 

 less sensitive to a touch than any others observed by 

 me. By gentle but repeated rubbing with a twig, the 

 lateral branches, but not the main stem, became in the 

 course of three or four hours slightly curved; but 

 they seemed to have hardly any power of again 

 straightening themselves. The tendrils of a plant which 

 had crawled over a large box-tree clasped several of the 

 branches ; but I have repeatedly seen that they will 

 withdraw themselves after seizing a stick. When they 

 meet with a flat surface of wood or a wall (and this 

 is evidently what they are adapted for), they turn 

 all their branches towards it, and, spreading them 

 widely apart, bring their hooked tips laterally into 

 contact with it. In effecting this, the several branches, 

 after touching the surface, often rise up, place them- 

 selves in a new position, and again come down into 

 contact with it. 



In the course of about two days after a tendril hat 

 arranged its branches so as to press on any surface, the 

 curved tips swell, become bright red, and form on 



* Trans. Phil. Soc. 1812, p. 314. 



