unlikely that they would move. Our observations were not very successful,
as the seedlings are strongly heliotropic, and their circumnutation could
not be accurately observed near a north-east window, although they had been
kept during the previous day in the same position. A seedling was then
placed in darkness with the hypocotyl secured to a stick; both cotyledons
rose a little at first, and then fell during the rest of the day; in the
evening between 5 and 6 P.M. they moved very slowly; during the night one
continued to fall and the other rose, though only a little. The tracing was
not much magnified, and as the lines were plainly zigzag, the cotyledons
must have moved a little laterally, that is, they must have circumnutated.

The hypocotyl is rather thick, about .12 of inch; nevertheless it
circumnutated in a complex course, though to a small extent. The movement
of an old seedling with two true leaves partially developed, was observed
in the dark. As the movement was magnified about 100 times it is not
trustworthy and is not given; but there could be no doubt that the
hypocotyl moved in all directions during the day, changing its course 19
times. The extreme actual distance from side to side through which the
upper part of the hypocotyl passed in the course of 14 ½ hours was only
1/60 of an inch; it sometimes travelled at the rate of 1/50 of an inch in
an hour.

Cucurbita ovifera (Cucurbitaceae).--Radicle: a seed which had

Fig. 26. Cucurbita ovifera: course followed by a radicle in bending
geotropically downwards, traced on a horizontal glass, between 11.25 A.M.
and 10.25 P.M.; the direction during the night is indicated by the broken
line. Movement of bead magnified 14 times.

germinated on damp sand was fixed so that the slightly curved radicle,