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Show 342 MODIFIED CIR 'Ul\:INU'l'A'l'ION. CHAP. VII. baRe of each leaflet is developed (at least in tho ca o of L. luteus) into a pulvinus. Tho result is that a1l tho leaflets on tho same loaf staud at night more or loss highly inclined, or oven quite vorticu.lly, forming in this latter case a vorticu.l star. This occurs with tho leaves of a species purchased under the namo of Fig. 138. L pubescens; and in tho accompanying figures we see at A (Fig. 138) tho loaves in their diurnal position; and at B the same plant at night with the two upper leaves having theh· leaflets almost vertical. At C another loaf, viewed laterally, is shown with the leaflets quite vertical. It is chiefly or exclusively the youngest loaves which form at night vertical stars. But there CHAP. VII. SLEEP OF LEAVE, . is much variability in the po ition of tho l avoB at night on the same plant; some remaining with their 1 aftots almost horizontal, others forming more or loss highly inclined or vertical stars and some with all their leaflets sloping down wards, as in our 'first class of cases. It is also a remarkable fact, that although all the plants produced from tho same lot of seedB wore identical in appearance, yet some individuu.ls at night had the I aflcts of all their leaves arranged so as to form more or loss highly inclined stars; others had them all sloping downwards and uovcr forming a star; and others, again, retained them either in a horizontal position or raised them a little. We have as yet referred only to the different positions of the leaflets of L. pubescens at night; but tho lJCtiolcs likcwi. e differ in their movements. That of a young leaf which formed a highly inclined star at night, stood at noon at 42° above the horizon, and during the night at 72°, so had risen 30°. 'l'he pet~o!e of a~other leaf, the leaflets of which occupied a similar poSltJOn ~t ~1ght, rose only 6°. On the other hand, tho petiole of a leaf With all its leaflets sloping down at ni()'ht fell at this time 4°. The petioles of two rather old.er lcav~s ~verc sub equently observed; both of which stood during the clay at exactly the same angle, viz., 50° above tho horizon and one of these ro ·o 7°-8°, and the other fell 3°-4° at night.' "W_e meet with cases like that of L. pubesce11s with some other species. ?n a single plant of L. mutabilis orne leave , which stoo~ hol'lZontally during the day, formecl highly inclined star,· at m~ht, and tho petiole of one ro e 7°. Other 1 aves which hkewisostood horizontally during tho day had at nio-ht all their lea~ets ~loping downwards at 46° benc~th tho h~rizon, but their petioles had hardly moved. .A gnin, L.lutcus offered a still more remarkable ca e, for on two leaves, tlw leaflets which stood atonoon at about 4.5o above the horizon, rose at night to 65° and ~9 • so that they formed a hollow cone with steep sides. Four n::s on the same. plant, which had their leaflets horizontal at ' formed vertical stars at ni!:rht · and tlu:ce other leaves equall]·· ~ ' · .J Y 10nzontal at uoon, had all their leaflets slopin()' down-warlls at · ht S o t . mg · o tllat tho leave · on this one plant a sumcd : ~t three different positions. Though we cannot account b~h to fact, .we ca~ see .that such a stock might readily give L. species havmg widely different nyctitropic habits p' Ittle mo reneed bo sai· d about tho sloop of the species ·o f Lu- Jnus; several, namely, L. polypltyllus, nanus, Menziesii, speciosus, |
