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On the first day the greater movement
(from right to left in the figure) was not in the plane of the vertical and
arched hypocotyl, but at right angles to it, or in the plane of the two
cotyledons, which were still in close contact. The basal leg of the arch at
the time when the filament was affixed to it, was already bowed
considerably backwards, or from the cotyledons; had the filament been
affixed before this bowing occurred, the chief movement would have been at
right angles to that shown in the figure. A filament was attached to
another buried hypocotyl of the same age, and it moved in a similar general
manner, but the line traced was not so complex. This hypocotyl became
almost straight, and the cotyledons were dragged from beneath the ground on
the evening of the second day.
Fig. 4. Brassica oleracea: circumnutating movement of buried and arched
hypocotyl, with the two legs of the arch tied together, traced on
horizontal glass during 33 ? hours. Movement of the bead of filament
magnified about 26 times, and here reduced to one-half original scale.


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