Fig. 8. Mean ± S.E.M. luminance (grayscale from 0-4095) for three peripheral stolon tips per replicate colony treated with H₂DCFDA. Unfilled bars represent the foreground luminance of the stolon tip; filled bars represent the background luminance of the surrounding area. (A) Controls; (B) 0.1 mg ml^-1 catalase. Colonies were imaged in a chamber containing plain seawater immediately after being removed from the treatment solution.