OCR Text |
Show 0-:1:0 MODIFIED OIROUMNUTATION. Crm. VII. whilst some, but not many, of those which had formerly stood facing the back of the room and wbich had never before been well illuminated or gone to sleep, now n.ssumed a vertical position at night. On the next day (12th) the plant was turned round into its originn.l position, so that tho same leaves faced the light as formerly, and those now wont to sleep in the usual manner. We will only add that with some young seedlings kept in the greenhouse, the blades of tho first pair of true leaves (the cotyledons being bypogean) .·tood during the day almost horizontally and at night n.lmost vertically. A few observations wore subsequently made on the circumnutation of three leaves, whilst facing a north-cast window; but the tracings are not given, as the leaves moved somewhat towards the light. It was, however, manjfest that they rose and fell more than once during the daytime, tho ascending and descending lines being in parts extremely zigzag. Tho nocturnal fall commenced about 7 P.M., and the loaves had risen considerably by 6.45 A.M. on tho following morning. Legumirwsre.-This Family inclu<los 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, ha been added. Crotolaria (sp. ?) (Tribe 2).-This plant is monophyllous, and we are informed by Mr. T. Thi ·elton Dyer that tho leaves rise up vertically at night and press again ·t the stem. Lttpinus (Tribe 2).-Tho 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 inclined downwards at night, having been during the day extended horizontally. This is shown in the accompanying figures (Fig. 137), of a loaf of L. pilosus, as seen during the day from vertically above, n.nd of another leaf asleep with the leaflets inclined downwards. As in this position they nre crowded together, and as they do not become folded like those in the genus Oxali , they cannot occupy a vertically dependent position; but they are often inclined at an angle of 50° beneath the horimn. In this species, whilst the leaflets are sinking, the petioles rise up, in two instances when the angles wero measured to the extent of 23°. The leaflets of L. sub-carnosus and arboreus, which were horizontal during the day, sank down ~t nio·ht in nearly the same manner· the former to an angle of 38' l'> ' • t' les and the latter of 36°, beneath the horizon; but their pe 10 CHAP. VII. SLEEP OF LEAVE, • :3-H did not move in any plainly perceptible degree. It is howev,. quite possible, as we shall presently see, that if a lar~e num:;;. of plants of the three foregoing and of the following specie~ Fig. 137. A. B. Lupinus pilosus: A, leaf seen from YCrtically nho,·c in daytime. n, lea f asleep, ·een lnterally at night. ' :eredto be obs~rved ~t all seasons, some of the leaves would lJe 1oun to sleep m a different manner. d In thedtwo !ollowing species the leaflets, instead of movinrr ownwta r s' rise at n I·g ht· WI't h L. 1· f artwegii some stood al:"t> ~~~: a mean a~gle of 36o above tho horizon, and at night stee '.~hus formmg. together a hollow cone with moderately no~t Sin~\~ The .petwle of one leaf rose 14o and of a second 65o bo g t. With L. l?tteus a leaflet rose from 47o at noon to rose afro~!~~ !o~;~n at nigh~, an<l another on a distinct leaf a small ex . ·. Tbe po~wlcs, however, sink at night to 0 . ~nt, VIz., m three mstances by 2o 6o and go 30' wmg to this movcm t f tl · ' ' · leaflets have to be d en o. le petioles, the outer and longer ones, in d t n up a httlo more than the shorter and inner We sh nor er hat all should stand symmetrically at night plants :f l~esently see ~hat some loaves on the same individuai We · uteus sleep m a very different manner. when~~= c;~.e t~ a remarkable position of the leaves On the sa~~ lea;ch lS common to several species of Lupine~;. centre of the tho s~orter leaflets, which generally face the on the oppos'tepl~dnt, ~mk at night, whilst the longer ones merelytwi t' 1 SI e rise •· the m· te rme d I·a t e and lateral one IV.I th respecst Intog on .t heir own axes. B u t tbe 1.o I·S some van.a bi. h.t y· expected from :hwh ~eafiets rise or fall. As might have been uch diverse and complicated movements, the ~ · . |