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166). Each leaflet is
provided with a well-developed pulvinus. When the leaves sleep, the two
terminal leaflets rise up, twist half round and come into contact with one
another (B), and are afterwards embraced by the two lower leaflets (C); so
that the four leaflets with their lower surfaces turned outwards form a
vertical packet. The curvature of the summit of the petiole of the leaf
figured asleep, is merely accidental. The plant was brought into a room,
where the temperature was only a little above 60o F., and the movement of
one of the leaflets (the petiole having been secured) was traced
[page 393]
during 24 h. (Fig. 167). The leaf fell from the early morning till 1.50
P.M., and then rose till 6 P.M., when it was asleep. A
Fig. 166. Marsilea quadrifoliata: A, leaf during the day, seen from
vertically above; B, leaf beginning to go to sleep, seen laterally; C, the
same asleep. Figures reduced to one-half of natural scale.
vertically dependent glass filament was now fixed to one of the terminal
and inner leaflets; and part of the tracing in Fig.


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