A somewhat different method of observation was next followed:
Fig. 3. Brassica oleracea: circumnutating movement of buried and arched
hypocotyl (dimly illuminated from above), traced on horizontal glass during
45 hours. Movement of bead of filament magnified about 25 times, and here
reduced to one-half of original scale.
as soon as the earth with seeds in a pot began to crack, the surface was
removed in parts to the depth of .2 inch; and a filament was fixed to the
basal leg of a buried and arched hypocotyl, just above the summit of the
radicle. The cotyledons were still almost completely enclosed within the
much-cracked seed-coats; and these were again covered up with damp adhesive
soil pressed pretty firmly down. The movement of the filament was traced
(Fig. 3) from 11 A.M. Feb. 5th till 8 A.M. Feb. 7th. By this latter period
the cotyledons had been dragged from beneath the pressed-down earth, but
the upper part of the hypocotyl still formed nearly a right angle with the
lower part. The tracing shows that the arched hypocotyl tends at this early
[page 14]
age to circumnutate irregularly.
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