14 



INHERITANCE IN POULTRY. 



heterozygous, both halves showing the dominant "absence of hernia." 

 The result agrees with expectation. 



4. Crest. — First hybrid generation. The crest is present in every hybrid 

 old enough to show a crest, yet always in reduced size. Crest is dominant, 

 but the dominance is imperfect. The crest is larger in the females (fig. 5) 

 than in the males (fig. 6). 



Second hybrid generation. All records, from embryo chicks as well as 

 adults, give : 



*Fig. n. 



Expectation is that crest will be absent in 25 per cent of the cases. The 

 excess is probably due to the fact that, since crest develops late, it was noted 

 as absent when it would have appeared in adult life. To test this I give a 

 table based on hatched chicks only : 



This gives a close approximation to expectation, with a slight excess of 

 crested individuals. The exact statistical proportion, with its possible errors 



