travelled irregularly during the whole of the following day and night of
June 22nd. The ascending and descending lines traced during the three days
did not coincide, so that the movement was one of circumnutation. This
seedling was then taken back to the hot-house, and after five days was
inspected at 10 P.M., when the cotyledons were found hanging so nearly
vertically down, that they might justly be said to have been asleep. On the
following morning they had resumed their usual horizontal position.

Oxalis rosea (Oxalideae).--The hypocotyl was secured to a little stick, and
an extremely thin glass filament, with two triangles of paper, was attached
to one of the cotyledons, which was .15 inch in length. In this and the
following species the end of the petiole, where united to the blade, is
developed into a pulvinus. The apex of the cotyledon stood only 5 inches
from the vertical glass, so that its movement was not greatly exaggerated
as long as it remained nearly horizontal; but in the course of the day it
both rose considerably above and fell beneath a horizontal position, and
then of course the movement was much exaggerated.
[page 24]
In Fig. 13 its course is shown from 6.45 A.M. on June 17th, to 7.40 A.M. on
the following morning; and we see that during the daytime, in the course of
11 h. 15 m., it travelled thrice down and twice up. After 5.45 P.M. it
moved rapidly downwards, and in an hour or two depended vertically; it thus
remained all night asleep. This position could not be represented on the
vertical glass nor in the figure here given. By 6.40 A.M. on the following
morning (18th) both cotyledons had risen greatly, and they continued to
rise until 8 A.M., when they stood almost horizontally. Their movement was
traced during the whole of this day and until the next morning; but a
tracing is not given, as it was closely similar to Fig. 13, excepting that
the lines were more zigzag. The cotyledons moved 7 times, either upwards or
downwards; and at about 4 P.M. the great nocturnal sinking movement