The tracing (Fig. 2, reduced by half) shows the
movement from 9 A.M. Jan. 31st to 7 A.M. Feb. 2nd; but it continued to move
during the whole of the
[page 12]
2nd in the same general direction, and in a similar zigzag manner. From the
radicle not being quite perpendicular when the filament was affixed
geotropism came into play at once; but the irregular zigzag course shows
that there was growth (probably preceded by turgescence), sometimes on one
and sometimes on another side. Occasionally the bead remained stationary
for about an hour, and then probably growth occurred on the side opposite
to that which caused the geotropic curvature. In the case previously
described the basal part of the very short radicle from being turned
vertically upwards, was at first very little affected by geotropism.
Filaments were affixed in two other instances to rather longer radicles
protruding obliquely from seeds which had been turned upside down; and in
these cases the lines traced on the horizontal glasses were only slightly
zigzag, and the movement was always in the same general direction, through
the action of geotropism.
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