12 



INHERITANCE IN POULTRY. 



On account of tlie difficulty of deciding in the case of any young chicks 

 whether ' no-median and no-splic comb ' is present, the last two classes are 

 combined in the right-hand column of this table and in columns a and p of the 

 table above. 



In comparing the fit of the expected percentages on the two hypotheses 

 with the actual, it is seen that hypothesis a is the better. However, the real 

 test will come in the Pj generation. On hypothesis a the single- combed 

 individuals bred together should produce only median-combed offspring. On 

 hypothesis /3 they should produce some without median comb.* 



First generation hybrids crossed with Minorca. When the Y-shaped comb is 

 crossed back on the single comb of the Minorca (No. 26 ^) the following 

 distribution of comb characters was obtained : 



Characteristic. 



Single comb 



Cleft comb. 



Papillae or "absent" 



Frequency. 



21 



ti9 

 o 



Per cent. 



52.5 



47- S 



0.0 



This result accords well with the expectation that 50 per cent of the 

 combs shall be of the pure Minorca type and 50 per cent of the heterozy- 

 gous type. 



2. Nostrils. — First generation. No case occurred of a typical high nostril; 

 this characteristic is dominated by the narrow nostril ; but this dominance 

 is imperfect. In three cases (5 per cent) the nostril is recorded as one-half 

 high, i. e., having an aperture one-half as high as the extreme. In the 

 other cases, placed in class 2, the breadth was less, but still evidently influ- 

 enced by the germinal representative of the " high " characteristic. In two 

 skulls that were dissected the processus nasalis of the premaxillary bone 

 was present. 



Second generation. In the second generation the high nostril appears again 

 in full or nearly full size in 2 1 per cent of the cases. Class 3 includes two 



*This topic is discussed again, generally, at page 68. 



t Including one thick comb with a median ridge in addition to the cleft comb, forming 

 a typical pea comb. Seen in unhatched chick XVIII, 103. 



