Fig. 22.

Short-period leaf movements of Ph. coccineus in continual darkness, first in the Posthauskeller, Akureyri, Iceland, and then after transfer to a growth chamber at the time and date indicated by the vertical line, whereupon the relatively short-period rhythm of movement becomes incorporated into a longer rhythm. Conventions which apply are the same as for Figs 2 and 3. Leaf trace redrawn from fig. 7 in Stoppel (1926).