One of them had developed some lateral or
secondary rootlets, which projected a few degrees beneath the horizon; and
it is an important fact that three of them left distinctly serpentine
tracks on the smoked surface, showing beyond doubt that they had
circumnutated like the main or primary radicle. But the tracks were so
slight that they could not be traced and copied after the smoked surface
had been varnished.
Fig. 29. Cucurbita ovifera: circumnutation of straight and vertical
hypocotyl, with filament fastened transversely across its upper end, traced
in darkness on a horizontal glass, from 8.30 A.M. to 8.30 P.M. The movement
of the terminal bead originally magnified about 18 times, here only 4 ?
times.
Hypocotyl.--A seed lying on damp sand was firmly fixed by two crossed wires
and by its own growing radicle. The cotyledons were still enclosed within
the seed-coats; and the short hypocotyl, between the summit of the radicle
and the cotyledons, was as yet only slightly arched. A filament (.85 of
inch in length) was attached at an angle of 35o above the horizon to the
side of the arch adjoining the cotyledons.
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