To summarize: "Potency," as measured by dominance of the extra-toed condition, is inherited, in the Houdan crosses at least.
The breed takes its name from the town of Houdan, the center of a district in which this is the common type of fowl.
The Polish and Houdan fowl thus retain in the outer nasal opening an embryonic condition.
It is also clear that the offspring of Silkie crosses are more apt to be polydactyl than those of Houdan crosses.
The wide-nostriled races used were both the Polish and the Houdan.
The Houdan has the size, deep compact body, short legs, and fifth toe of the Dorking.
Also the average degree of polydactylism is much greater in the Silkie than in the Houdan crosses.
A Houdan cockerel with bedraggled speckly plumage and a ragged crest hanging over one eye struts from doorstep to doorstep.