In two instances the
vertical arches were observed to move to a considerable distance backwards
from the point where the cotyledons lay buried; this movement, which has
been noticed in some other cases, and which seems to aid in extracting the
cotyledons from the buried seed-coats, is due to the commencement of the
straightening of the hypocotyl. In order to prevent this latter movement,
the two legs of an arch, the
Fig. 38. Solanum palinacanthum: circumnutation of an arched hypocotyl, just
emerging from the ground, with the two legs tied together, traced in
darkness on a horizontal glass, from 9.20 A.M. Dec. 17th to 8.30 A.M. 19th.
Movement of bead magnified 13 times; but the filament, which was affixed
obliquely to the crown of the arch, was of unusual length.
summit of which was on a level with the surface of the soil, were tied
together; the earth having been previously removed to a little depth all
round. The movement of the arch during 47 hours under these unnatural
circumstances is exhibited in the annexed figure.
The cotyledons of some seedlings in the hot-house were horizontal about
noon on December 13th; and at 10 P.
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