Chap. I, TWINING PLANTS. 21 



not move, a sort of hinge separating the moving and 

 the motionless part of the same intemode. After a 

 few days, however, I found that this lower part had 

 likewise recovered its revolving power. These several 

 facts show that the power of movement is not immedi- 

 ately lost in the arrested portion of a revolving shoot ; 

 and that after being temporarily lost it can be recovered. 

 When a shoot has remained for a considerable time 

 round a support, it permanently retains its spiral form 

 even when the support is removed. 



When a tall stick was placed so as to arrest the 

 lower and rigid internodes of the Ceropegia, at the 

 distance at first of 15 and then of 21 inches from the 

 centre of revolution, the straight shoot slowly and 

 gradually slid up the stick, so as to become more and 

 more highly inclined, but did not pass over the 

 summit. Then, after an interval sufficient to have 

 allowed of a semi-revolution, the shoot suddenly 

 bounded from the stick and fell over to the opposite 

 side or point of the compass, and reassumed its 

 previous slight inclination. It now recommenced 

 revolving in its usual course, so that after a semi- 

 revolution it again came into contact with the stick, 

 again slid up it, and again bounded from it and fell 

 over to the opposite side. This movement of the 

 shoot had a very odd appearance, as if it were 

 disgusted with its failure but was resolved to try- 

 again. We shall, I think, understand this movement 

 by considering the former illustration of the sapling, in 

 which the growing surface was supposed to creep round 



