* ‘Comptes Rendus,’ Jan. 1876, p. 171. [page 390]

the day or between 10o and 20o above the horizon, and at night vertically upwards.  They therefore rise between 70o and 90o at night.  The plant was placed at noon in the dark in the hot-house, and on the following day the movements of the leaves were traced.  Between 8.40 and 10.30 A.M. they rose, and then fell greatly till 1.37 P.M.  But by 3 P.M. they had again risen a little, and continued to rise during the rest of the afternoon and night; on the following morning they stood at the same level as on the previous day.  Darkness, therefore, during a day and a half does not interfere with the periodicity of their movements.  On a warm but stormy evening, the plant whilst being brought into the house, had its leaves violently shaken, and at night not one went to sleep.  On the next morning the plant was taken back to the hot-house, and again at night the leaves did not sleep; but on the ensuing night they rose in the usual manner between 70o and 80o.  This fact is analogous with what we have observed with climbing plants, namely, that much agitation checks for a time their power of circumnutation; but the effect in this instance was much more strongly marked and prolonged.

Colocasia antiquorum (Caladium esculentum, Hort.) (Aroideae).—­The leaves of this plant sleep by their blades sinking in the evening, so as to stand highly inclined, or even quite vertically with their tips pointing to the ground.  They are not provided with a pulvinus.  The blade of one stood at noon 1 degree beneath the horizon; at 4.20 P.M., 20o; at 6 P.M. 43o; at 7.20 P.M., 69o; and at 8.30 P.M., 68o; so it had now begun to rise; at 10.15 P.M. it stood at 65o, and on the following early morning at 11o beneath the horizon.  The circumnutation of another young leaf (with its petiole only 3 1/4 inches, and the blade 4 inches in length), was traced on a vertical glass during 48 h.; it was dimly illuminated through a skylight, and this seemed to disturb the proper periodicity of its movements.  Nevertheless, the leaf fell greatly during both afternoons, till either 7.10 P.M. or 9 P.M., when it rose a little and moved laterally.  By an early hour on both mornings, it had assumed its diurnal position.  The well-marked lateral movement for a short time in the early part of the night, was the only interesting fact which it presented, as this caused the ascending and descending lines not to coincide, in accordance with the general rule with circumnutating organs.  The movements of the leaves of this plant are thus of the most simple kind; and the tracing is not worth giving.  We have seen that in another genus of the Aroideae, namely, Pistia, the leaves [page 391] rise so much at night that they may almost be said to sleep.

Strephium floribundum* (Gramineae).—­The oval leaves are provided with a pulvinus, and are extended horizontally or declined a little beneath the horizon during the day.  Those on the upright culms simply rise up vertically at night, so that their tips are directed towards the zenith.  (Fig. 164.)