was probably beginning to descend, though the short line in the diagram is horizontal.  The actual distances travelled by the apex of the leaf were considerable, but could not be calculated with safety.  From the course pursued on the second day, when the plant had accommodated itself to the light from above, there cannot be much doubt that the leaves undergo a daily periodic movement, sinking during the day and rising at night.

(18.) Mutisia clematis (Compositae).—­The leaves terminate in tendrils and circumnutate like those of other tendril-bearers; but this plant is here mentioned, on account of an erroneous statement* which has been published, namely, that the leaves sink at night and rise during the day.  The leaves which behaved in this manner had been kept for some days in a northern room and had not been sufficiently illuminated.  A plant therefore was left undisturbed in the hot-house, and three leaves had their angles measured at noon and at 10 P.M.  All three were inclined a little beneath the horizon at noon, but one stood at night 2o, the second 21o, and the third 10o higher than in the middle of the day; so that instead of sinking they rise a little at night.

(19.) Cyclamen Persicum (Primulaceae, Fam. 135).—­A young leaf, 1.8 of an inch in length, petiole included, produced by an old root-stock, was observed during three days in the usual manner (Fig. 110).  On the first day the leaf fell more than afterwards, apparently from adjusting itself to the light from above.  On all three days it fell from the early morning to about 7 P.M., and from that hour rose during the night, the course being slightly zigzag.  The movement therefore is strictly periodic.  It should be noted that the leaf would have sunk each evening a little lower down than it did, had not the glass filament rested between 5 and 6 P.M. on the rim of the pot.  The amount of movement was considerable; for if we assume that the whole leaf to the base of the petiole became bent, the tracing would be magnified rather less than five times, and this would give to the apex a rise and fall of half an inch, with some lateral movement.  This amount, however, would not attract attention without the aid of a tracing or measurement of some kind.

* ‘The Movements and Habits of Climbing Plants,’ 1875, p. 118. [page 247]

(20.) Allamanda Schottii (Apocyneae, Fam. 144).—­The young leaves of this shrub are elongated, with the blade bowed so much

Fig. 110.  Cyclamen Persicum:  circumnutation of leaf, traced from 6.45 A.M.  June 2nd to 6.40 A.M. 5th.  Apex of leaf 7 inches from the vertical glass.