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40 A.M. to 10.45 P.M. Movements
of bead magnified about 26 times.
Cyclamen Persicum (Primulaceae).--This plant is generally supposed to
produce only a single cotyledon, but Dr. H. Gressner* has shown that a
second one is developed after a long interval of time. The hypocotyl is
converted into a globular corm, even before the first cotyledon has broken
through the ground with its blade closely enfolded and with its petiole in
the form of an arch, like the arched hypocotyl or epicotyl of any ordinary
dicotyledonous plant. A glass filament was affixed to a cotyledon, .55 of
an inch in height, the petiole of which had straightened itself and stood
nearly vertical, but with the blade not as yet fully expanded. Its
movements were traced during 24 ? h. on a horizontal glass, magnified 50
times; and in this interval it described two irregular small circles; it
therefore circumnutates, though on an extremely small scale.
Fig. 34. Stapelia sarpedon: circumnutation of hypocotyl, illuminated from
above, traced on horizontal glass, from 6.45 A.M. June 26th to 8.


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