It is remarkable that the
cotyledons do not generally rise at night to any conspicuous extent during
the first four or five days after germination; but the period was extremely
variable with seedlings kept under the same conditions; and many were
observed. Glass filaments with minute triangles of paper were fixed to the
cotyledons (1 ? mm. in breadth) of two seedlings, only 24 h. old, and the
hypocotyl was secured to a stick; their movements greatly magnified were
traced, and they certainly circumnutated the whole time on a small scale,
but they did not exhibit any distinct nocturnal and diurnal movement. The
hypocotyls, when left free, circumnutated over a large space.
Another and much older seedling, bearing a half-developed leaf, had its
movements traced in a similar manner during the three first days and nights
of June; but seedlings at this age appear to be very sensitive to a
deficiency of light; they were observed under a rather dim skylight, at a
temperature of between 16o to 17 1/2o C.' and apparently, in consequence of
these conditions, the great daily movement of the cotyledons ceased on the
third day.
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