232 



C1RCUMNUTATIOX OF LEAVES. 



CIIAP. 



petiole 



Fig. 97. 



very short, much movement could not be expected. 

 Nevertheless, the apex changed its course 

 completely seven times in the course of 

 Hi 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. 

 cjr (as shown in Fig. U7), and was nearly of 

 j ea f the same nature, but rather less complex. 

 6.40 The movement seems to be periodical, for 

 on both days the leaf circumnutated in tho 

 forenoon, fell in the afternoon (on the first 



from 



A.M. June 14th to 

 6.50 A.M. loth. 

 Apex of leaf 12 

 inches from the ver- day until between o and 4 P.M., and on the 

 tical glass, so figure 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 



considerably mag- 

 nified. Temp. 16- 

 16J C. 



6.30'n.m. 



10.S5'p.m.l 



Pelargonium zonale : circumnutation and downward movement of yottiijr 

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

 9| 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 



