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On Sept. 24th, between 8 A.M. and 5 P.M.,
the cotyledons moved five times up and five times down; they therefore
described five irregular ellipses in the course of the 9 h. The great
nocturnal rise commenced about 4.30 P.M.
On the following morning (Sept. 25th) the movement of the same cotyledon
was again traced in the same manner during 24 h.; and a copy of the tracing
is here given (Fig. 25). The morning was cold, and the window had been
accidentally left open for a short time, which must have chilled the plant;
and this probably prevented it from moving quite as freely as on the
previous day; for it rose only four and sank only four times during the
day, one of the oscillations being very small. At 7.10 A.M., when the first
dot was made, the cotyledons were not fully open or awake; they continued
to open till about 9 A.M., by which time they had sunk a little beneath the
horizon: by 9.30 A.M. they had risen, and then they oscillated up and down;
but the upward and downward lines never quite coincided. At about 4.30 P.M.
the great nocturnal rise commenced.


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