384 



MODIFIED CIECUMNUTATION. 



CHAP. VII. 



leaf had risen greatly, and continued to rise till 7.50 A.M., after 

 which hour it redescended. It should be observed that the lines 

 traced on this second morning would have coincided with and 

 confused those previously traced, had not the pot been slided 

 a very little to the left. In the evening (14th) a mark was 

 placed behind the filament attached to the apex of the leaf, and 

 its movement was carefully traced from 5 P.M. to 10.15 P.M. 



Fig. 161. 



Passiflora gracilis: circumnutation and nyctitropic movement of leaf, 

 traced on vertical glass, from 8.20 A.M. Oct. i3th to 10 A.M. 14th 

 Figure reduced to two-thirds of original scale. 



Between 5 and 7.15 P.M. the leaf descended in a straight line, 

 and at the latter hour it appeared vertically dependent. But 

 between 7.15 and 10.15 P.M. the line consisted of a succession 

 of steps, the cause of which we could not understand ; it was, 

 however, manifest that the movement was no longer a simple 

 descending one. 



Siegesbeckia orientalis (Compositse). Some seedlings were 

 raised in the middle of winter and kept in the hot-house ; they 

 flowered, but did not grow well, and their leaves never showed 

 any signs of sleep. The leaves on other seedlings raised in May 

 were horizontal at noon (June 22nd), and depended at a consi 



