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Four radicles were allowed to grow downwards over plates of smoked glass,
inclined at 70o to the horizon, under the
Fig. 27. Cucurbita ovifera: tracks left by tips of radicles in growing
downwards over smoked glass-plates, inclined at 70o to the horizon.
Fig. 28. Cucurbita ovifera: circumnutation of arched hypocotyl at a very
early age, traced in darkness on a horizontal glass, from 8 A.M. to 10.20
A.M. on the following day. The movement of the bead magnified 20 times,
here reduced to one-half of original scale.
same conditions as in the cases of Aesculus, Phaseolus, and Vicia.
Facsimiles are here given (Fig. 27) of two of these tracks; and a third
short one was almost as plainly serpentine as that at A. It was also
manifest by a greater or less amount of soot having been swept off the
glasses, that the tips had
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pressed alternately with greater and less force on them. There must,
therefore, have been movement in at least two planes at right angles to one
another. These radicles were so delicate that they rarely had the power to
sweep the glasses quite clean.


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