167, after 6 P.M.,
shows that it continued to sink, making one zigzag, until 10.40 P.M. At
6.45 A.M. on the following morning, the leaf was awaking, and the filament
pointed above the vertical glass,
Fig. 167. Marsilea quadrifoliata: circumnutation and nyctitropic movement
of leaflet traced on vertical glass, during nearly 24 h. Figure reduced to
two-thirds of original scale. Plant kept at rather too low a temperature.
but by 8.25 A.M. it occupied the position shown in the figure. The diagram
differs greatly in appearance from most of those previously given; and this
is due to the leaflet twisting and moving laterally as it approaches and
comes into contact with
[page 394]
its fellow. The movement of another leaflet, when asleep, was traced
between 6 P.M. and 10.35 P.M., and it clearly circumnutated, for it
continued for two hours to sink, then rose, and then sank still lower than
it was at 6 P.M. It may be seen in the preceding figure (167) that the
leaflet, when the plant was subjected to a rather low temperature in the
house, descended and ascended during the middle of the day in a somewhat
zigzag line; but when kept in the hot-house from 9 A.
Pages:
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660