The Behavior of Vermilion-suppressor in Mosaics

This fact indicates that the suppressor operates on a stage of the reaction other than that at which the difference between wild type and vermilion is established. It is interesting in this connection that the color changes in the pupal development of the eye of flies in which vermilion is suppressed resemble those of the wild type, not those of vermilion. The effect of the suppressor must therefore be exerted before the onset of pigment formation.