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Show 204 CIRCUMNU'fATION OF S'fEMS. CIIAP. IV. aid of their sensitive petioles, but some of thorn also twine round supports; but even these latter specie~ do not begin to circumnutate in a conspicuous manner wh1lst young. The Fig. 72. -----.:;..._ -·--v 'Irop<Eolum majus (?): circumnutation of stem of young plant, traced on a horizontal glass from 9 A.M. Dec. 26th to 10 A.M. on 27th. · Mov~m.ent of bead magnified about 5 times, and here reduced to half of ong1nal scale. variety here treated of has a rather thick stem, and is so dwarf that apparently it does not climb in any manner. Wo therefore wished to ascertain whether the stem of a young plant, Fig. 73. Trifolium resnpinatum : circumnutation of stem, traced on vertical glass from 9.30 A.M. to 4.30 P.M. Nov. 3rd. Tracing not greatly magnified, reduced to half of original size. Plant feebly illuminated from above. consisting of two internodes, together 3·2 inches in height, ciJcumnutated. It was observed during 25 h., and wo sec in Fig. 72 that tho stem moved in a zigzag course, indicatr ing circumnutation. (6.) 'J 'rifolittm resupinatum (Leguminosre, Fam. 75).- When we treat of tho sleep of plants, wo shall see that tho stems in several Leguminous genera, for instance, those of Hed~· sarum, Mimosa, Meli· lotus, &c., which are not climbers, circumnutate in a conspicuousman~er. We wi.l l here ~.v e only a sm. gle m. st ance (F. 73) showmg j 1g. • t.he circumnutation of the stem of a large plant of a clove~ Trifolium resupinatum. In the course of 7 h. the stem change CHAP. IV. CIRCUMNUTATION OF STEMS. 205 its course greatly eight times and completed three irregular circles or ellipses. It therefore circumnutated rapidly. Some of the lines run at right angles to one another. Rubus (hybrid): circumnutation of stem, traced on horizontal glass, from 4 P.M. March 14th to 8.::30 A.M. 16th. Tracing much magnified, reduced to half of original size. Plant illuminated feebly from above. (7.) Rubus idceus (hybrid) (Rosacero, Fam. 76).-As we happened to have a young plant, 11 inches in height and growing vigorously, which had been raised from a. cross between the raspberry (nub us idee us) and a North American Rubus, it was observed in the usual manner. During the morning of March 14th the stem almost completed a circle, and then moved far to the right. At 4 P.M. it reversed its course, nnd now a fresh tracing was begun, which was continued during 40~ h., and is given in Fig. 74. We here have well-marked circumnutation. Fig. 7 5. (8.) Deutzia gracilis (Saxifragere, Fam. 77).-A shoot on a bush abont l8 inches in height was observed. The ~ changed its course greatly eleven tlm.es in the course of 10 h. 30 m. Deut:zt'a gracilis: circumnu- (F tation of stem, kept. in Jg. 75), and there could be no darkness, traced on hori-doubt about the circumnutation of tbo zontal glass, from 8.30 sklm. A.M. to 7 P.M. March 20th. (9) F M ovcmcnt of bead origin- . uchsia (greenhouse var. with ally magnified about 20 larg ~ fl. OWers, probably a hybrid) ' (Ona- times, here reduood to gl'ariem F 100) A half scale. 15 inc ' ~m. . .- young plant, hes m hmght, wn.s obscrYed dm·ing nearly 48 h. The |
