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As far as we could roughly ascertain
by measurements made with compasses on other seeds, the tip alone, for a
length of only 2/100 to 3/100 of an inch, is acted on by geotropism. But
the tracing shows that the basal part of the radicle continued to
circumnutate irregularly during the whole time. The actual extreme amount
of movement of the bead at the end of the filament was nearly .05 inch, but
to what extent the movement of the radicle was magnified by the filament,
which was nearly 3/4 inch in length, it was impossible to estimate.
Fig. 1. Brassica oleracea: circumnutation of radicle, traced on horizontal
glass, from 9 A.M. Jan. 31st to 9 P.M. Feb. 2nd. Movement of bead at end of
filament magnified about 40 times.
Another seed was treated and observed in the same manner, but the radicle
in this case protruded .1 inch, and was not
Fig. 2. Brassica oleracea: circumnutating and geotropic movement of
radicle, traced on horizontal glass during 46 hours.
fastened so as to project quite vertically upwards. The filament was
affixed close to its base.


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