232 



CIHCUMNUTATION OF LEAVES. 



CIIAP. IV. 



petiole very short, much movement could not be expected 



Fig. 97. 



Nevertheless, the apex changed its course 

 completely seven times in the course of 

 11s h., but moved to only a very small 

 distance. On the next day the movement 

 of the apex was traced during 26 h. 20 m. 

 (as shown in Fig. 97), and was nearly of 

 the same nature, but rather less complex. 

 The movement seems to be periodical, for 

 on both days the leaf circumnutated in the 

 forenoon, fell in the afternoon (on the first 

 day until between 3 and 4 P.M., and on the 

 second day until 6 P.M.), and then rose, 

 falling again during the night or early 

 morning. 



In the chapter on the Sleep of Plants 

 we shall see that the leaves in several Malvaceous genera sink 



Fig. 98. 



Camellia Jaj>onica: cir- 

 cumnutation of leaf, 

 traced from 6.40 

 A.M. June 14th to 

 6.50 A.M. 15th. 

 Apex of leaf 12 

 inches from the ver- 

 tical glass, so figure 

 considerably mag- 

 nified. Temp. lt- 

 16J C. 



Pelargonium zonale : circumnutation and downward movement of young 

 leaf, traced from 9.30 A.M. June 14th to 6.30 P.M. 16th. Apex of leaf 

 9J inches from the vertical glass, so figure moderately magnified. 

 Temp. 15-16J C. 



at night; and as they often do not then occupy a vertical 

 position, especially if they have not been well illuminated during 



