24 



INHERITANCE IN POULTRY. 



Second hybrid generation. All individuals (26) whose face feathering was 

 observed are recorded as muffed; concerning a greater number (35) the 

 record is silent. What has become of the expected 25 per cent of muffless 

 individuals? It is possible, but on strict chance hardly probable, that the 

 uiufBess individuals all died young. A decisive answer to our question 

 must await further experimentation. 



First hybrid {Sy $ ) crossed i^'ith white Leghorn (7/ 9 )• Only one parent is 

 muffed. Muffed and non-muffed offspring occur in approximate equality ; 

 but even in the adult muffing is not full in amount. This cross confirms the 

 result of the first that muffing is dominant, but it is not perfectly so. 



6. Beard. — In \^i& first hybrid generation all individuals are bearded. When 

 these hybrids are crossed with the white I,eghorn about half of the offspring 

 are beardless. Beard is dominant. 



7. Cerebrai, Hernia. — \\xt\i& first hybrid generation all (24) individuals 

 were without external evidence of the cerebral hernia. In the second hybrid 

 generation out of 45 individuals 11 had the hernia (fig. 14) and 34 had 

 none, or 24.4 per cent and 75.6 per cent respectively. When the hybrid 

 zvas crossed zcith the white Leghorn (71$) no individual with the hernia 

 appeared. The cerebral hernia is a recessive characteristic. However, the 

 height of the frontal dome is variable, even in the pure-bred Houdans, and 

 on at least one occasion the cerebral prominence in an unhatched h5-brid 

 was so high that it was doubtful whether or not it might represent a hernia. 

 Here, as in Series I, plain-headedness, though clearly dominant, is imper- 

 fectly so. 



8. Crest. — First hybrid geyieration. Of 25 individuals all are crested. Hurst 

 (1905, p. 134) gets the same result. Second hybrid generatioii. Of 19 indi- 

 viduals 6 are non-crested, or 31.6 per cent, approaching the expected 25 per 

 cent. The remainder are crested. First hybrid {8j $ ) crossed with white 

 Leghorn (7/9)- Of 15 individuals 6, or 40 per cent, are without crest. 

 Expectation is 50 per cent. Crest is clearly dominant, yet in the first hybrid 

 it is never so large as in the Houdan. This fact is, I take it, due to imperfect 

 dominance. It may, however, be associated physiologically with the absence 

 of a cerebral hernia. 



9. Foot Color. — In the first hybrid generation this always becomes white in 

 the adult, although sometimes yellow in young birds. In the second genera- 

 tion of hybrids bred inter se or with the White L,eghorn stock, yellow reappears 

 as leg color. Statistics would be misleading on this point, as permanent leg 

 color is reached only on maturity. It may be concluded that white is domi- 

 nant over yellow. 



