14 



INHERITANCE OF CHARACTERISTICS IN DOMESTIC FOWL. 



parents and the percentage of single-combed offspring. These relations are 

 brought out in the lower haK of table 9. 



Tablb 9. — Frequency of the different proportion* of single element in the combs of offspring of parents 

 having the average proportion of median element given in the column at the left. 



The proportion of single-combed offspring in the total filial population 

 is 30.0 per cent, a departure of such magnitude from the expected 25 per 

 cent as to arrest our attention. Further inspection of table 9 shows that 

 the excess of single-combed offspring is found only in the lower half of the 

 series. When the percentage of median element in the parents is under 50 

 the proportions of I, Y, and no-median combs are as 25.5 per cent, 49.8 

 per cent, 24.7 per cent, or close to expectation; but when the percentage 

 is 50 or over the proportions are, on the average, 33.6 per cent, 45.2 per 

 cent, and 21.2 per cent, a wide departure from expectation, 1108 individuals 

 being involved. An examination of table 9 shows, moreover, that the pro- 

 portion of offspring with single comb rises steadily as the proportion of the 

 median element in the parentage increases from 50 per cent. The meaning 

 of this fact is at present obscure, but the suspicion is awakened that, while 

 the "cup comb" and the more deeply split combs are typical heterozygotes 

 the shghtly split combs are a complex of 2 or more units, one of which is 



