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Show 232 CIRCUMNUTATION OF LEAVES. 0IIA1'. IV. petiole very short, Fig. 97. :,\17\ ····~ much movement could not bo expected. Nevertheless, the apex changed its course completely seven times in tho course of 1H b., but moved to only a very small distance. On tho next clay tho movement of the apex was traced during 26 h. 20m. (as shown in Fig. 97), and was nearly of tho same nature, but rather less complex. The movement seems to be periodical, for on both days tho len.f circumnutatccl in the forenoon, fell in tho afternoon (on the first day until between 3 and 4 P.M., and on the second day until 6 P.M.), and then rose, falling again during the night or early morning. Camellia Japonica: circumnutation ofleaf, traced from 6.40 A.M. June 14th to 6.50 A.M. 15th. Apex of leaf 12 inches from the vertical glass, so figure considerably magnified. Temp. 16°- 16!0 c. In the chapter on the Sleep of Plants we shall sec that the leaves in several Malvaceous genera sink Fig. 98. 9•. 3o' a.m.t4tt!~ , JJ)~ IJS'.p .rrn. i r i \50'a . .n.1>'1> '?tl c·.:~o'p.m .. t6t?L i · to• .. ?5' p.?n.lf1~ Pelargonium zonale : circumnutation and downward movement of ~orn1 leaf, traced from 9.30 A.M . .Tunc 14th to 6.30 P.M. lGth. Apex 0 . 6~~. 9t inches from the vertical glass, so figure moderately magni Temp. 15°-1fi!° C. nt m•g ht; and as they often do not then occupy 11 verti,c. al position, especially if they have not been well illummated dunng CHAP. I.V. DICOTYLEDONS. 233 the day, it is doubtful whether some of those cases ought not to have been included in the present chapter. (7.) Pelargonium zonale (Geraniaceoo, Fam. 47).-A young · leaf, It inch in breadth, with its petiole 1 inch long, borne on a young plant, was observed in the usual manner during 61 h.; and its course is shown in the preceding figure (Fig. 98). During the first day and night the leaf moved downwards, but circumnutated between 10 A.M. and 4.30 P.M. On the second day it sank and rose again, but between 10 A.M. and 6 P.M. it circumnutated on an extremely small scale. On the third clay the circumnutation was more plainly marked. (8.) Gissu.~ discolor (Ampelideoo, Fam. 67).-A leaf, not nearly full-grown, the third from the apex of a shoot on a cut-down plant, was observed during 31 h. 30m. (see Fig. 99). The day was cold (15°-16° C.), and if the plant had been observed in the hot-house, the circumnutation, though plain enough as it was, would probably have been far more conspicuous. Fig. 99. (9.) Vicia faba (Leguminosoo, Fam. 75).-A young leaf, 3 ·1 inches in length, measured from base of petiole to end of leaflets, had a filament affixed to the midrib of one of the two terminal leaflets, and its movements wore traced during 5H h. The filament fell / all morning (July 2nd) till 3 P.M., and ,- th Cissus discolor: circumnu-en rose greatly till 10.35 P.M. ; but tation of leaf~ traced the rise .this day was so great, com- from 10.35 .A.l\1. May pared With that which subsequently 28th to 6 P.lii. 29th. OCCurred, that it was probably due in Apex of leaf 8£ inches part to the plant being illuminated from the vertical glass. f~~m a ?ave. The latter part of the course on July 2nd is alone ~ en m the following figure (Fig. 100). On the next day ta~ly .Brd) the l~af again fell in the morning, then circumnuthe dIn a conspiCuous manner, and rose tilllato at night; but fil movement was not traced after 7.15 P.M., as by that time the tha~ent pointed towards the upper edge of the glass. During 8 e atter part of the night or early morning it again fell in the ame manner as before. |