116 PULVINI OF COTYLEDONS. Chap. IL 



above it. After 24 days from the first observation (begun after 

 a true leaf had been developed) the cotyledons ceased to rise at 

 night. 



Oaalk {Blopliytum) seM.st<iya.— The cotyledons of several seed- 

 lings, 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 corniculuta.— The cotyledons do not stand vertical at 

 night, but generally rise to an angle of about 45° 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 hori- 

 zontal or downwardly deiiected 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. 



Tn/ulium suhterrancum. — A seedling, 8 days old, had its coty- 

 ledons 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 Jacolceus. — The cotyledons of soipe seedlings having 

 well-developed leaves rose to an angle of about 45° at night; 

 and even after 3 or 4 whorls of leaves had been formed, the co- 

 tyledons rose at night considerably above their diurnal hori- 

 zontal position. 



Cassia mimosoides. — The cotyledons of this Indian species, 

 14 dajs after their first expansion, and when a leaf had been 

 formed, stood during the day horizontal, and at night vertical. 

 Cassia sp ? (a large S. Brazilian tree raised from seeds sent us 



