26 



INHERITANCE IN POULTRY. 



white leg:s, 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. 

 CONCLUvSIONS. 



In the series of crosses between the White Leghorn and Houdan, Mendtlian 

 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, and crest, though always 

 present in the first hybrid generation, are apparent!}' alwaN's reduced. The 

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



A heterozygous for/n 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). 



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

 results, although suggestive, need support from other experiments. 



