The more perfectly serpentine tracks made by
the radicles of Phaseolus multiflorus and Vicia faba (presently to be
described), render it almost certain that the radicles of the present plant
circumnutated.
Fig. 18. Aesculus hippocastanum: outlines of tracks left on inclined
glass-plates by tips of radicles. In A the plate was inclined at 70o with
the horizon, and the radicle was 1.9 inch in length, and .23 inch in
diameter at base. In B the plate was inclined 65o with the horizon, and the
radicle was a trifle larger.
Phaseolus multiflorus (Leguminosae).--Four smoked glass-plates were
arranged in the same manner as described under Aesculus, and the tracks
left by the tips of four radicles of the present plant, whilst growing
downwards, were photographed as transparent objects. Three of them are here
exactly copied (Fig. 19). Their serpentine courses show that the tips moved
regularly from side to side; they also pressed alternately with greater or
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.
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