270 



MODIFIED CIRCUMNUTATION. 



CHAP. V. 



Fig. 121. 



young leaf was traced during 4 J days, and the tracing here given 

 (Fig. 121) shows that it descended at first in a nearly straight 

 line, but afterwards zigzagged, 

 making one or two little loops. 

 The diverging and descend- 

 ing movements of a rather 

 older leaf were also traced 

 (see former Fig. 113, p. 251) : 

 it descended during the first 

 day and night in a some- 

 what zigzag line ; it then cir- 

 cumnutated round a small 

 space and again descended. 

 By this time the leaf had 

 nearly assumed its final posi- 

 tion, and now plainly circum- 

 nutated. As in the case of the 

 Carnation, the leaves, whilst 

 very young, do not seem to be 

 much affected by geotropism 

 or heliotropism, for those on a 

 young plant laid horizontally, 

 and those on another plant 

 left upright, both kept in the 

 dark, continued to diverge in 

 the usual manner without 

 bending to either side. 



"With Cobcea scandens, the 

 young leaves, as they succes- 

 sively diverge from the lead- 

 ing shoot which is bent to 

 one side, rise up so as to pro- 

 ject vertically, and they retain 

 this position for some time 

 whilst the tendril is revolving, 

 The diverging and ascending 

 <* movements of the petiole of 



. , one such a leaf, were traced on 



xi-xu r*yster : epmastic downward . 



movecusnt of a young leaf, pro- a vertical glass under a sky- 



dnced by a young plant in a pot, light ; and the course pursued 



traced on a vertical glass under a was j n mos t par ts nearly 



rynght, from (3.45 A.M. June 2nd _.._ , . , , ,, . 



ight 

 to 10.40 P.M. Gth. 



straight, but there were twc 



