less force on the plates, sometimes rising up and leaving them altogether
for a very short distance; but this was better seen on the original plates
than in the copies. These radicles therefore were continually moving in all
directions--that is, they circumnutated. The distance between the extreme
right and left positions of the radicle A, in its lateral movement, was 2
mm., as ascertained by measurement with an eye-piece micrometer.

Fig. 19. Phaseolus multiflorus: tracks left on inclined smoked glass-plates
by tips of radicles in growing downwards. A and C, plates inclined at 60o,
B inclined at 68o with the horizon.

Vicia faba (Common Bean) (Leguminosae).--Radicle.--Some beans were allowed
to germinate on bare sand, and after one had protruded its radicle to a
length of .2 of an inch, it was turned upside down, so that the radicle,
which was kept in damp air, now stood upright. A filament, nearly an inch
in length, was affixed obliquely near its tip; and the movement of the
terminal bead was traced from 8.30 A.M. to 10.30 P.M., as shown in Fig. 18.
The radicle at first changed its course twice
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abruptly, then made a small loop and then a larger zigzag curve. During the
night and till 11 A.M. on the following

Fig. 20. Vicia faba: circumnutation of a radicle, at first pointing
vertically upwards, kept in darkness, traced on a horizontal glass, during
14 hours. Movement of bead of filament magnified 23 times, here reduced to
one-half of original scale.

morning, the bead moved to a great distance in a nearly straight line, in
the direction indicated by the broken line in the figure. This resulted
from the tip bending quickly downwards, as it had now become much declined,