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Show 210 CIRCUMNUTATION OF STEMS. CHAP. IV. 31 h. 40 m., and shows that it circumnutated. Tho bush was 15 inches in height. ~ . . . . . . nutation of stem, traced from 8.20 A.M. on March Aloysw C!trwdora · cn~u·md Pl t k pt in darkness. Movement magn1fied 22nd to 4 P.M. on 23I . an e about 40 times. l . d (?)(a scarlet-flowered herbaceous var.) (16) Verbena mew res · • l 1 ·a h · . . ) A h t 8 inches in height hac been m orJ· (Verbenacere .- s~:oof observing its apogcotropism, and the zontally, for the t' lly upwards for a length of t · 1 ortion had grown ver 1ca ermma p fil t 'th a bead at tho end, was fixec1 J t inches. A glass amen ' WI Fig. 82. -·---·------------------------------------· o•t:o'a ""' alh------ · 1 o " . . . d + s tracerl on vertJca Ver·bena melindres: circnmnutatJon of stem ID aJ ,ues 7 'th Movement of alass, from 5.30 P.M. on June 5th to 11 .A.:r.i. June · bead magnified 9 times. . t · traced dUl'JDg upright to tho tip, and its mo:emon s wore . these circum· 41 h. 30m. on a vertical glass (F1g. 82~. Unde~n. but as the Rtances tho lateral movements wore chiOfly sho • 1 tl 0 shoot lines from side to side are not on the same love ' 1 CHAP. IV. CIRCUMNUTATION OF • 'TEMS. 211 must have moved in a plano at right angles to thn.t of tho Jn.toral movement, that is, it must have circumnutatccl. On tho next day (6th) the shoot moved in the course ~f 16 h. four times to the right, and four times to tbc left; and th1s apparently represents tho formation of four ellipses, so that each was completed in 4 h. (17.) Ceratophyllum demersnm (Coratophyllcm, Fam. 220).-An interesting account of the movements of tho stem of this waterplant has been published by M. E. Rodier.* Tho movements are confined to the young internodes, becoming lc ·s and less lower down the stem; and they are extraordinary from their amplitude. The stems sometimes moved through an angle of above 200° in 6 h., and in one instance through 220° in 3 h. They generally bent from right to left in the morning, and in an opposite direction in the afternoon; but the movement was sometimes temporarily reversed or quite arrested. It was not affected by light. It does not appear that M. Rodier made any diagram on 11 horizontal plane representing the actual course pursucu by tbo apex, but he speaks of the "branches executing round their axes of growth a movement of torsion." From tho particulars 11bove given, and remembering in the case of twining plants and of tendrils, how difficult it is not to mistake their bending to all points of the compass for true torsion, wo arc led to believe that the stems of this Ceratophyllum circumnutato, probably in the shape of narrow ellipses, each completed in about 26 h. Tho following statement, however, seems to indicate something different from ordinary circumnutation, but we cannot fully understand it. M. Rodier says: "11 est alors facile de voir que le mouvement de flexion se produit d'abord dans los merithalles superieurs, qu'il so propage ensuite, on s'amoindri sant du lumt en bas; taudis qu'au contraire le rnouvoment de redressement commence par la partie inferieure pour so terminer a la partie superieure qui, quelquefois, peu de temps avant de se relovor touta fait, forme avec l'axe un angle tros aigu." (18.) Coniferre.-Dr. Maxwell Masters states (' J ournn.l Linn. Soc/ Dec. 2nd, 1879) that the leading shoots of many Coni£ rm durJng the season of their active growth exhibit very remarkatbtl e movements of revolv. inbO' nutation' that is' they circumnu-a 0 • We may feel sure that the lateral shoots whilst growing would exhibit the same movement if carefully observed. • 'C ubUs omptes Rendus,' April 30th. 1877. Also a second notice P hed separately in Bourdcaux, Nov. 12th, 1877. p 2 |