26 



INHERITANCE IN POULTRY. 



white legs, and toes that are usually but not always meristically abnormal. 

 When the hybrids are bred inter se we get varied combinations of char- 

 acteristics, as follows (D meaning dominant and R, recessive) : 



*Fig. 14. 



CONCLUSIONS. 



In the series of crosses between the White L/eghorn and Houdan, Mendelian 

 results were obtained as in the first series. Dominance, however, is frequently 

 imperfect. The plumage color of the offspring of a pure homogametous white- 

 and-black and a white are rarely pure white. Likewise in the second hybrid 

 generation impure whites occur. Also, nostril-height exhibits imperfect 

 dominance of the narrow type. The muff, beard, arid crest, though always 

 present in the first hybrid generation, are apparently alwaj^s reduced. The 

 cerebral hernia, though recessive, affects the dominant normal skull. 



A heterozygous form results from hybridizing the single and V-shaped comb. 

 The cleft comb is a neomorph, of which more will be said in the sequel 

 (page 65). 



Polydactylism does not readily fall into the Mendelian formula. Hurst's 

 results, although suggestive, need support from other experiments. 



