TIVIXEKS AND CLIMBERS. 209 



towards the light, and the other to the darkest side 

 of the house ; the latter did not move, but the oppo- 

 site one bent itself first upwards and then right 

 over its fellow, so that the two became parallel, one 

 above the other, both pointing to the dark. I then 

 turned the plant half-round, and the tendril which 

 had turned recovered its original position, and the 

 opposite one which had not before moved, now 

 turned over to the dark side. On another plant, 

 three pairs of tendrils were produced at the same 

 time by three shoots, and all happened to be 

 differently directed. I placed the pot in a box open 

 only on one side, and obliquely facing the light. 

 In two days all six tendrils pointed with unerring 

 truth to the darkest corner of the box, though to 

 do this each had to bend in a different manner. 

 Six wind-vanes could not have more truly shown 

 the direction of the wind than did these branched 

 tendrils the course of the stream of light which entered 

 the box. I left these tendrils undisturbed for about 

 twenty-four hours, and then turned the pot half- 

 round ; but they had now lost their power of move- 

 ment, and could not any longer avoid the light."^ 

 The rotation in the tendrils of some plants is 

 retarded and in others accelerated by the action of 



^ Darwin, " Movements of Climbing Plants,'' p. g8. 

 P 



