67. Brown, Jr. R. M. 1976. Phototaxis der
Grünalge Pyrobotrys. Institut für den Wissenschaftlichen
film. Wissenschaftlichen Film C 1171/1975 p 3-18. Göttingen.
This film shows a unique phototactic response
of the colonial green alga, Pyrobotrys. The most interesting
part of the film shows illumination of white light from 180 degrees,
causing the alga to swim into a concentrated mass. When the field
is viewed with red light (to which the algae do not respond) the
algae remain clumped but in relation to the amount of light exposure.
This suggests a chemotactic response takes place which is initiated
by the phototactic response to light. The proportionality of dose/response
is very interesting and seems to indicate that the clumping by
intertwining flagellae. The film will soon be in a video format.