[Role of the photoperiod in the reproductive function of female crabs, Pachygrapsus marmoratus (Fabricus)].

To enter vitellogenesis normally the females must pass through a period marked by a weak daily lighting which, it appears, triggers a determined physiological condition. If this state is not reached, vitellogenesis is impossible; on the contrary, if this state is reached, vitellogenesis is then accelerated by a long photophase. The results are discussed.