. The power of movement in plants . Plants; Botany. Ouip. IV. DICOTYLEDONS. 249 Fig. 112, (22.) Pttunia violaaa (Solanes3, Fam. 157).—A very young leaf, only i incli in length, highly inclined upwards, was observed for four days. During the whole of this time it bent outwards and downwards, so as to become more and more nearly hori- zontal. The strongly marked zigzag line in the figure on p. 248 (Fig. Ill), shows that this was effected by modified circum- nutation; and during the latter part of the time there was much ordinary circumnutation on a small scale. The movement in the diagram is mag
. The power of movement in plants . Plants; Botany. Ouip. IV. DICOTYLEDONS. 249 Fig. 112, (22.) Pttunia violaaa (Solanes3, Fam. 157).—A very young leaf, only i incli in length, highly inclined upwards, was observed for four days. During the whole of this time it bent outwards and downwards, so as to become more and more nearly hori- zontal. The strongly marked zigzag line in the figure on p. 248 (Fig. Ill), shows that this was effected by modified circum- nutation; and during the latter part of the time there was much ordinary circumnutation on a small scale. The movement in the diagram is magnified between 10 and 11 times. It exhibits a clear trace of periodicity, as the leaf rose a little each evening; but this upward tendency appeared to be almost conquered by the leaf striving to become more and more horizontal as it grew older. The angles which two older leaves formed together, were measured in the even- ing and about noon on 3 successive days, and each night the angle de- creased a little, though irregularly. (23.) Acanthus mollis (Acanthacese, Fam. 168). — The younger of two leaves, 21 inches in length, petiole included, produced by a seedling plant, was observed during 47 h. Early on each of the three morn- ings, the apex of the leaf fell; and it continued to fall tiU 3 , on the two afternoons when observed. After 3 it rose considerably, and continued to rise on the second night until the early morning. But on the first night it fell instead of rising, and we have little doubt that this was owing to the leaf being very young and becoming through epi- , nastic growth more and more hori- zontal; for it may be seen in the diagram (Fig. 112), that the leaf stood on a higher level on the first than on tne second day. The leaves of an allied species {A. spinosus) certainly rose every night; and the rise between noon and , when measured on one occasion, was 10°. This rise was chiefly. Acanthus tion of young leaf, traced f
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Keywords: ., bookcentury1800, booksubjectbotany, booksubjectplants, bookyear18
