Circadian oscillation controlling hatching: its ontogeny during embryogenesis of a moth.

Populations of eggs of the moth Pectinophora gossypiella develop a circadian rhythm of hatching activity under certain circumstances. This rhythm derives from circadian oscillations in each egg, which can be initiated or made synchronous by steps or pulses of either light or temperature, but only if these signals are administered after the midpoint of embryogenesis. Correlations between the development of the oscillation, appearance of a pigment, sensitivity to photoperiodic induction, and a possible effect of light on growth rate are discussed.