340 MODIFIED CIRCUMNUTATION. CHAP. VIL 



whilst some, but not many, of those which had formerly stood 

 facing the back of the room and which had never before been 

 well illuminated or gone to sleep, now assumed a vertical posi- 

 tion at night. On the next day (l'2th) the plant was turned 

 round into its original position, so that the same leaves faced 

 the light as formerly, and these now went to sleep in the usual 

 manner. We will only add that with some young seedlings 

 kept in the greenhouse, the blades of the first pair of true leaves 

 (the cotyledons being hypogean) stood during the day almost 

 horizontally and at night almost vertically. 



A few observations were subsequently made on the circum- 

 nutation of three leaves, whilst facing a north-east window ; but 

 the tracings are not given, as the leaves moved somewhat 

 towards the light. It was, however, manifest that they rose 

 and fell more than once during the daytime, the ascending and 

 descending lines being in parts extremely zigzag. The nocturnal 

 fall commenced about 7 P.M., and the leaves had risen consider- 

 ably by 6.45 A.M. on the following morning. 



Leguminosce. This Family includes many more genera with 

 sleeping species than all the other families put together. The 

 number of the tribes to which each genus belongs, according to 

 Bentham and Hooker's arrangement, has been added. 



Orotolaria (sp. ?) (Tribe 2). This plant is monophyllous, and 

 we are informed by Mr. T. Thiselton Dyer that the leaves rise 

 up vertically at night and press against the stem. 



Lupinus (Tribe 2). The palmate or digitate leaves of the 

 species in this large genus sleep in three different manners. 

 One of the simplest, is that all the leaflets become steeply in- 

 clined downwards at night, having been during the day ex- 

 tended horizontally. This is shown in the accompanying 

 figures (Fig. 137), of a leaf of L. pilosus, as seen during the 

 day from vertically above, and of another leaf asleep with the 

 leaflets inclined downwards. As in this position they are 

 crowded together, and as they do not become folded like those 

 in the genus Oxalis, they cannot occupy a vertically dependent 

 position ; but they are often inclined at an angle of 50 beneath 

 the horizon. In this species, whilst the leaflets are sinking, 

 the petioles rise up, in two instances when the angles were 

 measured to the extent of 23. The leaflets of L. sub-carnosus and 

 arboreus, which were horizontal during the day, sank down at 

 night in nearly the same manner ; the former to an angle of 38, 

 and the latter of 36, beneath the horizon : but their petioles 



