The observations were made under a rather dim skylight,
and the temperature during the whole time was between 17 1/2o to 18o C. (63o
to 65o F.). Had the temperature been higher and the light brighter, the
movements would probably have been greater. On July 11th (see Fig. 30), the
cotyledon fell from 7.35 A.M. till 10 A.M.; it then rose (rapidly after 4
P.M.) till it stood quite vertically at 8.40 P.M. During the early morning
of the next day (12th) it fell, and continued to fall till 8 A.M., after
which hour it rose, then fell, and again rose, so that by 10.35 P.M. it
stood much higher than it did in the morning, but was not vertical as on
the preceding night. During the following early morning and whole day
(13th) it fell and circumnutated, but had not risen when observed late in
the evening; and this was probably due to the deficiency of heat or light,
or of both. We thus see that the cotyledons became more widely open at noon
on each succeeding day; and that they rose considerably each night, though
not acquiring a vertical position, except during the first two nights.
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