An Hereditary Complex in the Domestic Fowl.

Brachydactyly, syndactyly, and leg-feathering or ptilopody‘ are among the many characteristics of the domestic fowl that have been studied from the standpoint of genetics. The last in particular, owing to its widespread occurrence, has aroused especial interest. Its heredity has been investigated by HURST (1905), DAVENPORT (1909), and more recently by PUNNETT and BAILEY ( 1918). The genetic behavior of syndactyly has been studied by DAVENPORT (1909) and that of brachydactyly by DANFORTH (1919 a). The purpose of this paper is to present evidence that these three characteristics, at first sight apparently distinct and unrelated, are in reality the product of a single gene or a single combination of genes. The possibility that this is the case was suggested in the earlier paper on brachydactyly, but at the time that paper was written, sufficiently critical breeding tests had not been made, the suggestion being based largely on morphological evidence. The additional data now available, while not abundant, seem to be significant, and are therefore put on record. Except where otherwise indicated the descriptions and data are all from individuals derived, on one side at least, from a single family, the relationships of the principal members of which are shown in the accompanying pedigree chart. None of those indicated in the chart was syndactyl.