356 



MODIFIED CIRCUMNUTATION. 



CHAP. VII. 



pudica ; but, from standing further apart, they do not overlap 

 one another nearly so much as in this latter plant. The main 

 petiole is curved slightly downwards during the day, but 

 straightens itself at night. In three cases it rose from 3 above 

 the horizon at noon, to 9 at 10 P.M. ; from 11 to 33; and from 

 5 to 33 the amount of angular movement in this latter case 

 amounting to 28. In several other species of Coronilla the 

 leaflets showed only feeble movements of a similar kind. 



Hedysarum coronarium (Tribe 6). The small lateral leaflets 

 on plants growing out of doors rose up vertically at night, but 

 the large terminal one became only moderately inclined. The 

 petioles apparently did not rise at all. 



Smithia Pfundii (Tribe 6). The leaflets rise up vertically, 

 and the main petiole also rises considerably. 



Arachis hypogcea (Tribe 6). The shape of a leaf, with its two 

 pairs of leaflets, is shown at A (Fig. 147) ; and a leaf asleep, 



Fig. 147. 



A B. 



Arachis hypogcea : A, leaf during the day, seen from vertically above ; B, 

 leaf asleep, seen laterally ; copied from a photograph. Figures much 

 reduced. 



traced from a photograph (made by the aid of aluminium 

 light), is given at B. The two terminal leaflets twist round at 

 night until their blades stand vertically, and approach each 

 other until they meet, at the same time moving a little upwards 

 and backwards. The two lateral leaflets meet each other in the 

 same manner, but move to a greater extent forwards, that is, in 

 a contrary direction to the two terminal leaflets, which they 

 partially embrace. Thus all four leaflets form together a single 

 packet, with their edges directed to the zenith, and with their 

 lower surfaces turned outwards. On a plant which was not 

 growing vigorously the closed leaflets seemed too heavy for the 



