His backcross data were as follows (Knox, 1927, p. 120): Parents Black Buff F,(Buff Orpington/Blac Buff Orpington Fn(Buff Orpington/Blac Black Langshan F-, (Buff 0rpington/Whi1 Buff Orpington Fn(Buff Orpington/Whit White Plymouth Rock These are adult plumage classifications rather than those based on chick down as he notes (Knox, ly27, p. 113): ...many of the black chicks develop into birds whose adult plumage would be classified as buffs, while chicks classed as buffs very rarely develop adult plumage which would place them in the black group. His conclusion from the above data was (Knox, 1927, p. 119