We have here a remarkable instance of the power of light in retarding and hastening the revolving movement. (See Errata.)
Convolvulus sepium (large-flowered cultivated var.) moves against the sun. Two circles, were made each in 1 hr. 42 m.: difference in semicircle from and to the light 14 m.
Rivea tiliæfolia (Convolvulaceæ) moves against the sun, made four revolutions in 9 hrs.; so that, on an average, each was performed in 2 hrs. 15 m.
Plumbago rosea (Plumbaginaceæ) follows the sun. The shoot did not begin to revolve until nearly a yard in height; it then made a fine circle in 10 hrs. 45 m. During the next few days it continued to move, but irregularly. On August 15th the shoot followed, during a period of 10 hrs. 40 m., a long and deeply zigzag course and then made a broad ellipse. The figure apparently represented three ellipses, each of which averaged 3 hrs. 38 m. for its completion.
Jasminum pauciflorum, Bentham (Jasminaceæ), moves against the sun. A circle was made in 7 hrs. 15 m., and a second rather more quickly.
Clerodendrum Thomsonii (Verbenaceæ) follows the sun.
| H. | M. | ||
| April 12, 1st circle was made in | 5 | 45 | (shoot very young) |
| 14, 2nd | 3 | 30 | |
| 18, a semicircle | 5 | 0 | (directly after the plant was shaken on being moved) |
| 19, 3rd circle | 3 | 0 | |
| 20, 4th | 4 | 20 |
Tecoma jasminoides (Bignoniaceæ) moves against the sun.
| H. | M. | ||
| March 17, 1st circle was made in | 6 | 30 | |
| 19, 2nd | 7 | 0 | |
| 22, 3rd | 8 | 30 | (very cold day) |
| 24, 4th | 6 | 45 |
Thunbergia alata (Acanthaceæ) moves against sun.