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Show 246 CIRCU1\1NUTA'l'ION Ol!' LEAVES. CHAP. IV. clay the leaf descended from 8.20 A.M. till7.15 P.M., then zigzn.gged and ascended greatly during tho night. On the morning of the 20th the loaf was probably beginning to descend, though the short line in the diagram is horizon tal. The actual distances travelled by the apex of the leaf were consiuerable, but could not be calculated with safety. From tho course pursued on the , econd day, when the plant had accommodatecl itself to tho light from above, there cannot be much doubt that tho leaves undergo a daily periodic movement, sinking during tho day and rising nt night. (18.) Mutisia clematis (Compositro).-Tho leaves terminate in tendrils and circumnutato like those of other tendril-bearers; but this plant is here mentioned, on account of an erroneous statement* which bas been published, namely, that tho leaves sink at night and rise during tho day. The leaves which behaved in this manner had boon kept for some days in a northern room and had not boon sufficiently illuminated. A plant therefore was left undisturbed in tho hot-house, and three leaves had their angles measured at noon and at 10 P.M. All three were inclined a little bencn.th tho horizon at noon, but one stood at night 2°, the second 21°, and tho third 10° higher than in the middle of tho day; so that instead of sinking they rise a little at night. (19.) Cyclnmen Per·sicum (Primulaccro, Fam. 135).-A young leaf, 1·8 of an inch in length, petiole included, produced by an old root-stock, was observed during throe days in tho usual manner (Fig. 110). On the first day the leaf fell more than after· wards, apparently from adjusting itself to tho light from above. On all three clays it fell from the early morning to about 7 P.M., and from that hour rose during tho night, tho courso being slightly zigzag. Tho movement therefore is strictly periodic. It should be noted that the leaf would have sunk each evening a little lower down than it did, had not the glass filament rested between 5 and 6 P.M. on tho rim of tho pot. Tho amount of movement was considerable ; for if we assume that the whole loaf to the base of the petiole became bent, tho tracing W0\ 1ld be magnified rather less than five times, and this would gJVe to the apex a rise and fall of half an inch, with some lat~ral movement. This amount however would not attract attentiOn without the aid of a traci~g or mea~uromont of some kind. * 'The Movements and Habits of Climbing Plants,' 1875, P· llS. CHAP. IV. DICOTYLEDONS. (20.) Allamanda Sch.ottii (Apocynere, Fam. 144).-The young leaves of this shrub are elongated, with tho blade bowed so much Fig. 110. 6' 4~ a.m.2'~ \ i I 1 i / / ff 50' a.m.st!' \ 6 '40'a .m.<.Jd.h \ \ \ \ i \ ~ I Cycl p, 6'5'.,.m.4~'h ~:~ 40 ersioum: circumnutation of leaf, traced from 6.45 A.M. June 2nd· • A.M. 5th. Apex of leaf 7 inches from the vertical glass. ~o~~ards as almost to form a semicircle. The chord-that p\~ tne drawn from the apex of the blade to the base of the 6 10 &-<>fa young leaf, 4i inches in length, stood at 2.50 P.M. on |