344 flIODIFIED CIKUCfMNUTATlON. Chap. VII. 



and albifrons, though observed out of doors and in the green- 

 house, did not change the position of their leaves sufficiently at 

 night to be said to sleep. Prom observations made on two 

 sleeping species, it appears that, as with Tropmolum majus, the 

 leaves must be well illuminated during the day in order to sleep 

 at night. For several plants, kept all day in a sitting-room 

 with north-east windows, did not sleep at night ; but when the 

 pots were placed on the following day out of doors, and were 

 brought in at night, they slept in the usual manner. The trial 

 was repeated on the following day and night with the same 

 result. 



Some observations were made on the ciroumnutation of the 

 leaves of L. luteus and arb;reus. It will suffice to say that the 

 leaflets of the latter exhibited a double oscillation in the course 

 of 24 h. ; for they fell from the early morning until 10 15 a.m., 

 then rose and zigzagged greatly till 4 p.m., after which hour the 

 great nocturnal fall commenced. By 8 a.m. on the following 

 morning the leaflets had risen to their proper height. We have 

 seen in the fourth chapter, that the leaves of l.upinus speciosus, 

 which do not sleep, circumnutate to an extraordinary extent, 

 making many ellipses ia the course of the day. 



Cyfisus (Tribe 2), Trigonella and Medicago (Tribe 3). — Only 



Fig. 139. 



A. B. 



■0 marina A. leaves during the d.iv ; B, leaves asleep at night. 



A few observations were made on these three genera. Tha 

 petioles on a young p'ant, about a foot in height, of Cytisus 

 fragraiis rose at night, on one occasion 23° and on another 33°. 

 The three leaflets' alsi bend upwards, and at the same time 



