(11.) Hedera helix (Araliaceae, Fam. 114).—­The stem is known to be apheliotropic, and several seedlings growing in a pot in the greenhouse became bent in the middle of the summer at right angles from the light.  On Sept. 2nd some of these stems were tied up so as to stand vertically, and were placed before a north-east window; but to our surprise they were now decidedly heliotropic, for during 4 days they curved themselves towards the light, and their course being traced on a horizontal glass, was strongly zigzag.  During the 6 succeeding days they circumnutated over the same small space at a slow rate, but there could be no doubt about their circumnutation.  The plants were kept exactly in the same place before the window, and after an interval of 15 days the stems were again observed during 2 days and their movements traced, and [page 208] they were found to be still circumnutating, but on a yet smaller scale.

(12.) Gazania ringens (Compositae, Fam. 122).—­The circumnutation of the stem of a young plant, 7 inches in height, as measured to the tip of the highest leaf, was traced during 33 h., and is shown in the accompanying figure (Fig. 78).  Two

Fig. 78.  Gazania ringens:  circumnutation of stem traced from 9 A.M.  March 21st to 6 P.M. on 22nd; plant kept in darkness.  Movement of bead at the close of the observations magnified 34 times, here reduced to half the original scale.

main lines may be observed running at nearly right angles to two other main lines; but these are interrupted by small loops.

(13.) Azalea Indica (Ericineae, Fam. 128).—­A bush 21 inches in height was selected for observation, and the circumnutation of its leading shoot was traced during 26 h. 40 m., as shown in the following figure (Fig. 79).

(14.) Plumbago Capensis (Plumbagineae, Fam. 134).—­A small lateral branch which projected from a tall freely growing bush, at an angle of 35o above the horizon, was selected for observation.  For the first 11 h. it moved to a considerable distance in a nearly straight line to one side, owing probably to its having been previously deflected by the light whilst standing in the greenhouse.  At 7.20 P.M. on March 7th a fresh tracing was begun and continued for the next 43 h. 40 m. (see Fig. 80).  During the first 2 h. it followed nearly the same direction as before, and then changed it a little; during the night it moved at nearly right angles to its previous course.  Next [page 209] day (8th) it zigzagged greatly, and on the 9th moved irregularly round and round a small circular space.  By 3 P.M. on the 9th the figure had become so complicated that no more dots could be made; but the shoot continued during the evening of the 9th, the whole of the 10th, and the morning of the 11th to

Fig. 79.  Azalea Indica:  circumnutation of stem, illuminated from above, traced on horizontal glass, from 9.30 A.M.  March 9th to 12.10 P.M. on the 10th.  But on the morning of the 10th only four dots were made between 8.30 A.M. and 12.10 P.M., both hours included, so that the circumnutation is not fairly represented in this part of the diagram.  Movement of the bead here magnified about 30 times.