230 



CIRCUMNUTATION- OF LEAVES. CHAP. 



Fig 102. 



Fig. 103. 



(10.) Acacia rctinoides (Leguminosae). The movement of a 



young phyllode, 2 inches in length, and inclined at a consider- 

 able angle above the horizon, was traced 

 during 45 h. 30 in. ; but in the figure here 

 given (Fig. 102), its circumnutation is shown 

 during only 21 h. 30 m. During part of 

 this time (viz., 14 h. 30 m.) the phyllode 

 described a figure re- 

 presenting 5 or 6 

 small ellipses. The 

 actual amount of 

 movement in a ver- 

 tical direction was '3 

 inch. The phyllode 

 rose considerably be- 

 tween 1.30 P.M. and 

 4 P.M., but there was 

 no evidence on either 

 day of a regular pe- 

 riodic movement. 



(11.) Lvpintis s r c- 

 ciosus (Leguminosre). 

 Plants were raised 



from seed purchased under this name. 



This is one of the species in this large 



genus, the leaves of which do not sleep 



at night. The petioles rise direct from 



the ground, and are from 5 to 7 inches 



in length. A filament was fixed to the 



midrib of one of the longer leaflets, and 



the movement of the whole leaf was traced, 



as shown in Fig. 103. In the course of 



6 h. 30 m. the filament went four times up 



and three times down. A new tracing 



was then begun (not hero given), and 



during 12^ h. the leaf moved eight times 



up and seven times down; so that it 



described 7j ellipses in this time, and 



this is an extraordinary rate of movement. 



The summit of the petiole was then secured 



to a stick, and the separate leaflets were found to be continually 



circumnutating. 



Acacia retino'des : cir- 

 cumnutation of a 

 young phyllode, 

 traced from 10.45 

 A.M. July 18th to 

 8.15 A.M. 19th. 

 Apex of phyllode 9 

 inches from the 

 vertical glass; tern p. 

 16i-17J C. 



: cir- 

 ' leaf 

 traced on vertical 

 glass, from 10.15A.M. 

 to 5.45 P.M.; i.e., 

 during 6 h. 30 m. 



