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 tiliaefolia (Convolvulaceae) 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 (Plumbaginaceae) 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 (Jasminaceae), moves against the sun. A circle was made in 7 hrs. 15 m., and a second rather more quickly.

Clerodendrum Thomsonii (Verbenaceae) follows the sun.

                                        H.   M.
April 12, 1st circle was made in         5   45 (shoot very young)
      14, 2nd                            3   30
                                                {(directly after the
       18, a semicircle                  5    0 { plant was shaken
                                                { on being moved)
       19, 3rd circle                    3    0
       20, 4th                           4   20

Tecoma jasminoides (Bignoniaceae) 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 (Acanthaceae) moves against sun.

                                          H.  M.
April 14, 1st circle was made in          3   20
      18, 2nd                             2   50
      18, 3rd                             2   55
      18, 4th                             3   55 (late in afternoon)

Adhadota cydonaefolia (Acanthaceae) follows the sun. A young shoot made a semicircle in 24 hrs.; subsequently it made a circle in between 40 hrs. and 48 hrs. Another shoot, however, made a circle in 26 hrs. 30 m.

Mikania scandens (Compositae) moves against the sun.

                                          H.  M.
March 14, 1st circle was made in           3  10
      15, 2nd                              3   0
      16, 3rd                              3   0
      17, 4th                              3  33
April  7, 5th                              2  50
       7, 6th                              2  40

{This circle was made {after a copious watering with cold water at 47 degrees Fahr.)

Combretum argenteum (Combretaceae) moves against the sun. Kept in hothouse.

H. M. {Early in morning, when Jan. 24, 1st circle was made in 2 55 the temperature of the house had fallen a little.

     24, 2 circles each at an }
           average of         }           2   20
     25, 4th circle was made in           2   25

Combretum purpureum revolves not quite so quickly as C. argenteum.

Loasa aurantiaca (Loasaceae). Revolutions variable in their course: a plant which moved against the sun.

                                       H.   M.
June 20, 1st circle was made in         2   37
     20, 2nd                            2   13
     20, 3rd                            4    0
     21, 4th                            2   35
     22, 5th                            3   26
     23, 6th                            3    5

Another plant which followed the sun in its revolutions.

                                       H.   M.
July 11, 1st circle was made in         1   51 }
     11, 2nd                            1   46 } Very hot day.
     11, 3rd                            1   41 }
     11, 4th                            1   48 }
     12, 5th                            2   35 }

Scyphanthus elegans (Loasaceae) follows the sun.

The Movements and Habits of Climbing Plants Page 12

Charles Darwin

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