afternoon in a nearly straight line, until between 6 and 7 P.M., when they
stood vertically. During the latter part of the night, or more probably in
the early morning, they began to fall or open, so that by 6.45 A.M. they
stood fully expanded and horizontal. They continued to fall slowly for some
time, and during the second day described a single small ellipse, between 9
A.M. and 2 P.M., in addition to the great diurnal movement. The course
pursued during the whole 24 h. was far less complex than in the foregoing
case of Cassia. On the third morning they fell very much, and then
circumnutated on a small scale round the same spot; by 8.20 P.M. they
showed no tendency to rise at night. Nor did the cotyledons of any of the
many other seedlings in the same pot rise; and so it was on the following
night of June 5th. The pot was then taken back into the hot-house, where it
was exposed to the sun, and on the succeeding night all the cotyledons rose
again to a high angle, but did not stand quite vertically. On each of the
above days the line representing the great nocturnal
[page 37]
rise did not coincide with that of the great diurnal fall, so that narrow
ellipses were described, as is the usual rule with circumnutating organs.
The cotyledons are provided with a pulvinus, and its development will
hereafter be described.

Mimosa pudica (Leguminosae).--The cotyledons rise up vertically at night,
so as to close together. Two seedlings were observed in the greenhouse
(temp. 16o to 17o C. or 63o to 65o F.). Their hypocotyls were secured to
sticks, and glass filaments bearing little triangles of paper were affixed
to the cotyledons of both. Their movements were traced on a vertical glass
during 24 h. on November 13th. The pot had stood for some time in the same
position, and they were chiefly illuminated through the glass-roof. The
cotyledons of one of these seedlings moved downward in the morning till
11.30 A.M., and then rose, moving rapidly in the evening until they stood