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.  During the first two days they began rising in the early 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 vertically, so that in this case there was simply a single great daily fall and rise.  The other seedling behaved rather differently, for it fell in the morning until 11.30 A.M., and then rose, but after 12.10 P.M. again fell; and the great evening rise did not begin until 1.22 P.M.  On the following morning this cotyledon had fallen greatly from its vertical position by 8.15 A.M.  Two other seedlings (one seven and the other eight days old) had been previously observed under