summit of which was on a level with the surface of the soil, were tied together; the earth having been previously removed to a little depth all round.  The movement of the arch during 47 hours under these unnatural circumstances is exhibited in the annexed figure.

The cotyledons of some seedlings in the hot-house were horizontal about noon on December 13th; and at 10 P.M. had risen to an angle of 27o above the horizon; at 7 A.M. on the following [page 52] morning, before it was light, they had risen to 59o above the horizon; in the afternoon of the same day they were found again horizontal.

Beta vulgaris (Chenopodeae).—­The seedlings are excessively sensitive to light, so that although on the first day they were uncovered only during two or three minutes at each observation, they all moved steadily towards the side of the room whence the light proceeded, and the tracings consisted only of slightly zigzag lines directed towards the light.  On the next day the plants were placed in a completely darkened room, and at each observation were illuminated as much as possible from vertically above by a small wax taper.  The annexed figure (Fig. 39) shows the movement of the hypocotyl during 9 h. under these circumstances.  A second seedling was similarly observed at the same time, and the tracing had the same peculiar character, due to the hypocotyl often moving and returning in nearly parallel lines.  The movement of a third hypocotyl differed greatly.

Fig. 39.  Beta vulgaris:  circumnutation of hypocotyl, with filament fixed obliquely across its summit, traced in darkness on horizontal glass, from 8.25 A.M. to 5.30 P.M.  Nov. 4th.  Movement of bead magnified 23 times, here reduced to one-third of original scale.

We endeavoured to trace the movements of the cotyledons, and for this purpose some seedlings were kept in the dark, but they moved in an abnormal manner; they continued rising from 8.45 A.M. to 2 P.M., then moved laterally, and from 3 to 6 P.M. descended; whereas cotyledons which have been exposed all the day to the light rise in the evening so as to stand vertically at night; but this statement applies only to young seedlings.  For instance, six seedlings in the greenhouse had their cotyledons partially open for the first time on the morning of November 15th, and at 8.45 P.M. all were completely closed, so that they might properly be said to be asleep.  Again, on the morning of November 27th, the cotyledons of four other seedlings, which were surrounded by a collar of brown paper so that they received light only from above, were open to the extent of 39o; at 10 P.M. they were completely closed; next morning (November 28th) at 6.45 A.M. whilst it was still dark, two of them [page 53] were partially open and all opened in the course of the morning; but at 10.20 P.M. all four (not to mention nine others which had been open in the morning and six others on another occasion) were again completely closed.  On the morning of the 29th they were open, but at night only one of the four was closed, and this only partially; the three others had their cotyledons much more raised than during the day.  On the night of the 30th the cotyledons of the four were only slightly raised.