In view of the present interest in the development of commercial poultry flocks by crossing inbred lines, at least two questions of importance arise. One is, how well does a successful cross between two inbred lines repeat itself with successive generations of the particular parental lines involved? The other, bound up with the manifest degenerative change that seems to be the fate of most inbred lines, is related to the possibility of determining minimal and/or optimal degrees of inbreeding necessary to produce commercially satisfactory offspring.

As a preliminary to a major investigation of these problems it would perhaps be useful to record briefly observations on small groups of pullets derived from such a cross, which has been repeated at intervals over 11 years within the Centre's flock of Brown Leghorn fowls, and to compare them with the parental lines.