Evidence that the mottled (mo) and pied (pi) plumage genes of the domestic fowl are identical.

1. An investigation was conducted among the progeny from crosses between Exchequer Leghorn and Ancona bantams into the relationship between two plumage phenotypes, pied and mottled, both of which are arrangements of non-pigmentation expressed on a background of eumelanin. 2. Both the pied and mottled phenotypes had previously shown to be caused by recessive genes, denoted pi and mo respectively. 3. The progeny consisted entirely of intermediaries between the two parental phenotypes, indicating that pi and mo are one and the same gene for which I retain the symbol mo.