Fig. 7. The commencement of ecdysis-triggering hormone (ETH)-induced ecdysis in larvae after treatment with CO₂ or N₂. (A) Larvae were injected with 200 pmol of ETH (at 0 min) and 20 min later were treated with CO₂ or N₂ for 1 min (white arrowheads). (B) Larvae were treated with CO₂ for 1 min, at various times after ETH injection, as noted on the y-axis and by arrowheads. Controls (C) were handled at 20 min after ETH injection. The bars represent mean times + S.E.M. Letters represent significant differences from controls and from each other within groups (P<0.001), as determined by analysis of variance using the Tukey test for differences (=0.05).