8 



INHERITANCE OF CHARACTERISTICS IN DOMESTIC FOWL. 



precise proportion of 3 : 1, yet such should be the commonest families if 

 the second hypothesis were true. Notwithstanding the marked deviation 

 to be discussed later from the expected proportions of I, 25 per cent; 

 Y, 50 per cent; oo, 25 per cent, the result accords better with the first or 

 third hypothesis. Since on either of these hypotheses the same proportions 

 of the various types of comb are to be expected in the progeny of Y-combed 

 parents of whatever generation, it is worth recording that from such parents 

 belonging to all generations except the first the results given in table 4 

 were obtained, and it will be noticed that these results approach expecta- 

 tion on the first or third hypothesis. 



Table 4. 



The progeny of two extracted single-combed parents of the F^ genera- 

 tion give in 3 famihes the following totals: Of 95 F3 offspring, 94 have 

 single combs; one was recorded from an unhatched chick as having a 

 slightly split comb, but this was probably a single comb with a slight side- 

 spur, a form that is associated with purely l-combed germ-cells. This result 

 is in perfect accord with the second and third hypotheses, but is irreconcil- 

 able with the first hypothesis. 



The progeny of two extracted 00-combed parents is given in table 5. 



Table 5. 



* Median element recorded as "small " in these offspring. t A median element visible in the mother. No. 2618. 



The distribution of offspring in the 24 families of table 5 is in fair 

 accord with any of the three hypotheses, but seems to favor the second, 

 for that hypothesis calls for families with combless children, whereas such 

 are not to be expected on the first hypothesis. Moreover, agreement 

 with the second hypothesis is fairly close, for that calls for 3 families 

 with combless children and there were actually 3 such families showing 

 a total of 1.8 per cent combless, where expectation is 2.8 per cent. What 



