(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. (20.) Allamanda Schottii (Apocyneae, Fam. 144).—The young leaves of this shrub are elongated, with the blade bowed so much downwards as almost to form a semicircle. The chord—that is, a line drawn from the apex of the blade to the base of the petiole—of a young leaf, 4 3/4 inches in length, stood at 2.50 P.M. on Dec. 5th at an angle of 13° beneath the horizon, but by 9.30 P.M. the blade had straightened itself so much, which implies the raising of the apex, that the chord now stood at 37° above the horizon, and had therefore risen 50°. On the next day similar angular measurements of the same leaf were made; and at noon the chord stood 36° beneath the horizon, and 9.30 P.M. 3½° above it, so had risen 39½°. The chief cause of the rising movement lies in the straightening of the blade, but the short petiole rises between 4° and 5°. On the third night the chord stood at 35° above the horizon, and if the leaf occupied the same position at noon, as on the previous day, it had risen 71°. With older leaves no such change of curvature could be detected. The plant was then brought into the house and kept in a north-east room, but at night there was no change in the curvature of the young leaves; so that previous exposure to a strong light is apparently requisite for the periodical change of curvature in the blade, and for the slight rising of the petiole. 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. (21.) Wigandia (Hydroleaceae, Fam. 149).—Professor Pfeffer informs us that the leaves of this plant rise in the evening; but as we do not know whether or not the rising is great, this species ought perhaps to be classed amongst sleeping plants.