INHERITANCE OF FECUNDITY 179 



We may next consider the theoretical results which would be 

 expected to follow the mating in all possible combinations of 

 birds of the constitutions set forth above. In doing this account 

 will be taken of female progeny 07ily, for the sake of simplicity, 

 saving of space, and because we are here concerned only with 

 actual fecundity as expressed in the female. Anyone who desires 

 can easily work out the cf constitutions for himself. Tables 9 

 and 10 give the expected numbers of female progeny from each 

 mating, on the assumption of uniform fertility throughout. It 

 will be seen that some odd ratios should appear. 



It should be pointed out that while, for the sake of complete- 

 ness, the result of every possible mating is carried out in table 9 

 on an assumption of equal fertility for all matings, this by no 

 means accords with actual fact. Certain of the matings would 

 not in practice get any offspring at all. This applies also to table 

 10. This point will be made clear in connection with the appli- 

 cation of the theoretical frequencies to the observed data. 



It will not be necessary in the table for Cornish Indian Games 

 to present the theoretical frequencies in such detail. Only totals 

 and ratios will be given. 



From table 10 it will be seen that no high layers are to be 

 expected from pure Cornish Game matings and that further the 

 proportion of zero layers is relatively high. 



ANALYSIS OF THE EXPERIMENTAL DATA 



In this section the actual results in respect to fecundity will 

 be compared with the theoretical expectations. There will be 

 presented first the data respecting the matings of Barred Rock 

 males and females (pure B.P.R. matings); second the data 

 respecting matings of Cornish Indian Game males and females 

 (pure C.I.G. matings); and finally the Fi and F^ matings of 

 Barred Plymouth Rocks and Cornish Indian Games crossed 

 reciprocally. 



Since the actual breeding operations were carried out in advance 

 of any understanding of the mechanism of the inheritance of 

 fecundity the matings were substantially at random so far as con- 



