nodosa, are thick and fleshy, and do not
rise up at night. The circumnutation of the cotyledons during the day of C.
tora has been described in the first chapter. Although the cotyledons of
Smithia sensitiva rose from a horizontal position in the middle of the day
to a vertical one at night, those of S. Pfundii, which are thick and
fleshy, did not sleep. When Mimosa pudica and albida have been kept at a
sufficiently high temperature during the day, the cotyledons come into
close contact at night; otherwise they merely rise up almost vertically.
The circumnutation of those of M. pudica has been described. The cotyledons
of a Bauhinia from St. Catharina in Brazil stood during the day at an angle
of about 50o above the horizon, and at night rose to 77o; but it is
probable that they would have closed completely, if the seedlings had been
kept in a warmer place.
Lotus.--In three species of Lotus the cotyledons were observed to sleep.
Those of L. Jacoboeus present the singular case of not rising at night in
any conspicuous manner for the first 5 or 6 days of their life, and the
pulvinus is not well developed at this period.
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