DEVELOPMENTAL GENETICS IN LOWER PLANTS 813
Figure 6 Video images showing the response to 90° reorientation of an apical protonemal cell of
Physcomitrella patensgrown in infrared light. Times after reorientation are shown. The large arrow provides a
reference point for the measurement of growth rate and was repositioned immediately after reorientation. The
arrowhead denotes the position of the nucleus. (From Ref. 60.)