Eosin is allelomorphic to white and the white-eosin compound or Heterozygote has the color of the eosin male.
"Sex-linked Inheritance in Drosophila"
Thomas Hunt Morgan Calvin B. Bridges
Since the Heterozygote in F1 was deeply pigmented, it is certain that a bird with only a small amount of pigment in its skin was a recessive resulting from incomplete segregation of the pigmented character.
"Hormones and Heredity"
J. T. Cunningham
The condition bred true, as pure recessives do; and when such an impure recessive was mated with a Heterozygote with black skin, the offspring were half pigmented and half recessive, with some pigment on the abdomen of the latter.
"Hormones and Heredity"
J. T. Cunningham