and had thus gained a position highly favourable for the action of
geotropism.
Fig. 21. Vicia faba: tracks left on inclined smoked glass-plates, by tips
of radicles in growing downwards. Plate C was inclined at 63o, plates A and
D at 71o, plate B at 75o, and plate E at a few degrees beneath the horizon.
[page 31]

We next experimented on nearly a score of radicles by allowing them to grow
downwards over inclined plates of smoked glass, in exactly the same manner
as with Aesculus and Phaseolus. Some of the plates were inclined only a few
degrees beneath the horizon, but most of them between 60o and 75o. In the
latter cases the radicles in growing downwards were deflected only a little
from the direction which they had followed whilst germinating in sawdust,
and they pressed lightly on the glass-plates (Fig. 21). Five of the most
distinct tracks are here copied, and they are all slightly sinuous, showing
circumnutation. Moreover, a close examination of almost every one of the
tracks clearly showed that the tips in their downward course had
alternately pressed with greater or less force on the plates, and had
sometimes risen up so as nearly to leave them for short intervals. The
distance between the extreme right and left positions of the radicle A was
0.7 mm., ascertained in the same manner as in the case of Phaseolus.

Epicotyl.--At the point where the radicle had protruded from a bean laid on
its side, a flattened solid lump projected .1 of an inch, in the same
horizontal plane with the bean. This protuberance consisted of the convex
summit of the arched epicotyl; and as it became developed the two legs of
the arch curved themselves laterally upwards, owing to apogeotropism, at
such a rate that the arch stood highly inclined after 14 h., and vertically
in 48 h. A filament was fixed to the crown of the protuberance before any
arch was visible, but the basal half grew so quickly that on the second