M. July 26th to 9 A.M. on 27th.
Glass filament fixed transversely across peduncle, near flower-head.
Fig. 192. Trifolium subterraneum: movement of same peduncle, with
flower-head completely buried beneath the sand; traced from 8 A.M. to 7.15
P.M. on July 29th.
The movement of another vertically dependent peduncle with the flower-head
standing half an inch above the ground, was traced, and again when it first
touched the ground; in both cases irregular ellipses were described every 4
or 5 h. A peduncle on a plant which had been brought into the house, moved
from an upright into a vertically dependent position in a single day; and
here the course during the first 12 h. was nearly straight, but with a few
well-marked zigzags which betrayed the essential nature of the movement.
Lastly the circumnutation of a peduncle was traced during 51 h. whilst in
the act of burying itself obliquely in a little heap of sand. After it had
buried itself to such a depth that the tips of the sepals were alone
visible, the above figure (Fig 191) was traced during 25 h.
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