Die Schwärmperiodizität von Platynereis dumerilii im DD/LD-Belichtungszyklus und nach Augenausschaltung

If periods with DD and LD alternate regularly the maximum of the swarming Heteronereis is nearly as distant from the beginning of DD as it is, under the alternation of LL- and LD-periods, from the beginning of LD. This supports the assumption that the position of the swarming maximum is determined by the moment at which the time of the daily illumination is shortened. Blind Platynereis under the alternation of LL- and LD-periods have the same swarming periodicity as those with normal sight. Therefore the photoperiodic influences do not effect through the eyes.