Fig. 9. Distribution of entrained adult eclosion (A) and responses to CO₂ during adult eclosion (B—E). (A) The entrainment period consisted of 2 weeks in a 17 h:7 h light:dark cycle coupled to a thermoperiod of 28 °C:25 °C. The start of the scotophase is depicted by the shaded column at 15:00 h Pacific Standard Time (PST). The frequency of eclosion is depicted for 189 animals. (B—E) The ability of CO₂ to induce premature eclosion in entrained pharate adults. Animals were treated with CO₂ for 1 min at various times (pink arrows) before lights out. Each pair of points (open and filled circle) and a cross represent eclosion behaviours from one animal (sample). Since the onset of the abdominal and thoracic components of ecdysis (pink open and filled circles, respectively) often occurred separately in CO₂-treated animals, they are separated temporally on the graph. When behaviours occurred in immediate succession, the dots were overlaid as a circle with a dotted center. Controls, in which abdominal and thoracic behaviours always occurred in immediate succession (thus open circles containing black dots), are shown in black. The time when the wings are fully expanded and move to the `moth' position is depicted by a cross for each animal.