Chap VII. 



SLEEP OF LEAVES. 



353 



Fig. U4. 



Loti's (Tribe 4).— The nyctitropic movements of 10 species 

 in tliis genus were observed, and found to be the same. The 

 main petiole rises a little at night, and 

 the three leaflets rise till they become 

 vertical, and at the same time approach 

 each other. This was conspicuous with 

 L. JacohcEus, in which the leaflets are 

 almost linear. In most of the species 

 the leaflets rise so much as to press 

 against the stem, and not rarely they 

 become inclined a little inwards with 

 their lower surfaces exposed obliquely 

 to the zenith. This was clearly the 

 case with L. major, as its petioles are 

 unusually long, and the leaflets are thus 

 enabled to bend further inwards. The 

 young leaves on the summits of the 

 stems close up at night so much, as 

 often to resemble large buds. The 

 stipule-like leaflets, which are often of 

 large size, rise up like the other leaflets, 

 and press against the stem (Fig. 145). 

 All the leaflets of L. Oehelii, and pro- 

 bably of the other species, are provided 

 at their bases with distinct pulvini, of 

 a yellowish colour, and formed of very 

 small cells. The circumnutation of a 

 terminal leaflet of L. periyrinvs (with 

 the stem secured) was traced during 

 two days, but the movement was so 

 sim])le that it is not worth while to 

 give the diagram. The leaflet fell 

 slowly from the early morning till 

 about 1 P.M. It then rose gradually 

 at first, but rapidly late in the evening. 



It occasionally stood still for about 20 m. during the day, and 

 sometimes zigzagged a little. The movement of one of the 

 basal, stipule-like leaflets was likewise traced in the same 

 manner and at the same lime, and its course was closely similar 

 to that of the terminal leaflet. 



In Tribe 5 of Bentham and Hooker, the sleep-movementa 

 of species in 12 genera have been observed by ourselves and 



TrifoUum repens : ci rcura 

 nutation and nyctitropic 

 movements of a nearly 

 full - grown terminal 

 leaflet, traced on a ver- 

 tical glass from 7 A.M. 

 Sept. 30th to 8 A.M. Oct. 

 1st. Nocturnal course, 

 represented by tui'ved 

 broken line, much ab- 

 breviated. 



