Cotyledons.—On two occasions the movements of the cotyledons were traced on a vertical glass, and as the ascending and descending lines did not quite coincide, very narrow ellipses were formed; they therefore circumnutated. Whilst young they rise vertically up at night, but their tips always remain reflexed; on the following morning they sink down again. With a seedling kept in complete darkness they moved in the same manner, for they sank from 8.45 A.M. to 4.30 P.M.; they then began to rise and remained close together until 10 P.M., when they were last observed. At 7 A.M. on the following morning they were as much expanded as at any hour on the previous day. The cotyledons of another young seedling, exposed to the light, were fully open for the first time on a certain day, but were found completely closed at 7 A.M. on the following morning. They soon began to expand again, and continued doing so till about 5 P.M.; they then began to rise, and by 10.30 P.M. stood vertically and were almost closed. At 7 A.M. on the third morning they were nearly vertical, and again expanded during the day; on the fourth morning they were not closed, yet they opened a little in the course of the day and rose a little on the following night. By this time a minute true leaf had become developed. Another seedling, still older, bearing a well-developed leaf, had a sharp rigid filament affixed to one of its cotyledons (85 mm. in length), which recorded its own movements on a revolving drum with smoked paper. The observations were made in the hot-house, where the plant had lived, so that there was no change in temperature or light. The record commenced at 11 A.M. on February 18th; and from this hour till 3 P.M. the cotyledon fell; it then rose rapidly till 9 P.M., then very gradually till 3 A.M. February 19th, after which hour it sank gradually till 4.30 P.M.; but the downward movement was interrupted by one slight rise or oscillation about 1.30 P.M. After 4.30 P.M. (19th) the cotyledon rose till 1 A.M. (in the night of February 20th) and then sank very gradually till 9.30 A.M., when our observations ceased. The amount of movement was greater on the 18th than on the 19th or on the morning of the 20th.