Fig. 20.

Short-period leaf movements (τ approx. 6–8 h) of Ph. coccineus in continual darkness, first in the Posthauskeller, Akureyri, Iceland, and then after transfer to the Islandbankkeller at the time and date indicated by the vertical line. Conventions which apply to the panels of this figure are as for Figs 2 and 3. Leaf trace redrawn from fig. 3 in Stoppel (1926).