Fig. 6.  Brassica oleracea:  conjoint circumnutation of the hypocotyl and cotyledons during 10 hours 45 minutes.  Figure here reduced to one-half original scale.

made on the glass.  The last was made at 8.45 P.M.; seventeen dots being altogether made in this interval of 10 h. 45 m. (see Fig. 6).  It should be noticed that when I looked shortly after 4 P.M. the bead was pointing off the glass, but it came on again at 5.30 P.M., and the course during this interval of 1 h. 30 m. has been filled up by imagination, but cannot be far from correct.  The bead moved seven times from side to side, and thus described 3 ½ ellipses in 10 3/4 h.; each being completed on an average in 3 h. 4 m.

On the previous day another seedling had been observed under similar conditions, excepting that the plant was so [page 17] placed that a line joining the two cotyledons pointed towards the window; and the filament was attached to the smaller cotyledon on the side furthest from the window.  Moreover the plant was now for the first time placed in this position.  The cotyledons bowed themselves greatly towards the light from 8 to 10.50 A.M., when the first dot was made (Fig. 7).  During the

Fig. 7.  Brassica oleracea:  conjoint circumnutation of the hypocotyl and cotyledons, from 10.50 A.M. to 8 A.M. on the following morning.  Tracing made on a vertical glass.

next 12 hours the bead swept obliquely up and down 8 times and described 4 figures representing ellipses; so that it travelled at nearly the same rate as in the previous case. during the night it moved upwards, owing to the sleep-movement of the cotyledons, and continued to move in the same direction till 9 A.M. on the following morning; but this latter movement would not have occurred with seedlings under their natural conditions fully exposed to the light.

By 9.25 A.M. on this second day the same cotyledon had [page 18] begun to fall, and a dot was made on a fresh glass.  The movement was traced until 5.30 P.M. as shown in (Fig. 8), which is given, because the course followed was much more irregular than on the two previous occasions.  During these 8 hours the bead changed its course greatly 10 times.  The upward movement of the cotyledon during the afternoon and early part of the night is here plainly shown.

Fig. 8.  Brassica oleracea:  conjoint circumnutation of the hypocotyl and cotyledons during 8 hours.  Figure here reduced to one-third of the original scale, as traced on a vertical glass.

As the filaments were fixed in the three last cases to one of the cotyledons, and as the hypocotyl was left free, the tracings show the movement of both organs conjoined; and we now wished to ascertain whether both circumnutated.  Filaments were therefore fixed horizontally to two hypocotyls close beneath the petioles of their cotyledons.  These seedlings had stood for two days in the same position before a north-east window.  In the morning, up to about 11 A.M.,