270 



MODIFIED CIECUMNUTATION. 



C'UAl-. V. 



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

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



line, but afterwards zigzagged, 



Fig. 121. 



P:re.«, roister : epinastic downward 

 Jiioveriient of a young leaf, pro- 

 duced by a young plant in a pot, 

 traced on a vertical glass under a 

 BKyiight, from 0.45 a.m. June 2nd 

 to 10.40 P.M. 0th. 



making one or two little loops. 

 The diverging and descend- 

 ing movements of a rather 

 older leaf were also traced 

 (see former Fig. 118, p. 251) : 

 it descended during the first 

 day and night in a some- 

 what zigzag line ; it then cir- 

 ciimnutated 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 

 bonding to either side. 



With Coi<ea 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 ou 

 a vertical glass under a sky- 

 light ; and the coiu-se pursued 

 was in most parts nearly 

 straight, but there were twc 



