[Oxalis Valdiviana.—­Some cotyledons which had lately opened and were horizontal on March 6th at noon, stood at night vertically up; on the 13th the first true leaf was formed, and was embraced at night by the cotyledons; on April 9th, after an interval of 35 days, six leaves were developed, and yet the cotyledons rose almost vertically at night.  The cotyledons of another seedling, which when first observed had already produced a leaf, stood vertically at night and continued to do so for 11 additional days.  After 16 days from the first observation two leaves were developed, and the cotyledons were still greatly raised at night.  After 21 days the cotyledons during the day were deflected beneath the horizon, but at night were raised 45o [page 116] above it.  After 24 days from the first observation (begun after a true leaf had been developed) the cotyledons ceased to rise at night.

Oxalis (Biophytum) sensitiva.—­The cotyledons of several seedlings, 45 days after their first expansion, stood nearly vertical at night, and closely embraced either one or two true leaves which by this time had been formed.  These seedlings had been kept in a very warm house, and their development had been rapid.

Oxalis corniculata.—­The cotyledons do not stand vertical at night, but generally rise to an angle of about 45o above the horizon.  They continued thus to act for 23 days after their first expansion, by which time two leaves had been formed; even after 29 days they still rose moderately above their horizontal or downwardly deflected diurnal position.

Mimosa pudica.—­The cotyledons were expanded for the first time on Nov. 2nd, and stood vertical at night.  On the 15th the first leaf was formed, and at night the cotyledons were vertical.  On the 28th they behaved in the same manner.  On Dec. 15th, that is after 44 days, the cotyledons were still considerably raised at night; but those of another seedling, only one day older, were raised very little.

Mimosa albida.—­A seedling was observed during only 12 days, by which time a leaf had been formed, and the cotyledons were then quite vertical at night.

Trifolium subterraneum.—­A seedling, 8 days old, had its cotyledons horizontal at 10.30 A.M. and vertical at 9.15 P.M.  After an interval of two months, by which time the first and second true leaves had been developed, the cotyledons still performed the same movement.  They had now increased greatly in size, and had become oval; and their petioles were actually .8 of an inch in length!

Trifolium strictum.—­After 17 days the cotyledons still rose at night, but were not afterwards observed.

Lotus Jacoboeus.—­The cotyledons of some seedlings having well-developed leaves rose to an angle of about 45o at night; and even after 3 or 4 whorls of leaves had been formed, the cotyledons rose at night considerably above their diurnal horizontal position.

Cassia mimosoides.—­The cotyledons of this Indian species, 14 days after their first expansion, and when a leaf had been formed, stood during the day horizontal, and at night vertical.