37 



If fertility be governed by genes transmitted in Mendelian fashion and without 

 sex-hnkage, this fact should be brought out by correlating the sire's record with his 

 son's record. The only measure is the fertility record of the eggs laid by females 

 mated to such males. If it were possible to compare males by a system of mating 

 to the same group of females, the variable factors could be reduced to the male 

 side alone. Such a system seems impossible to attain because of numerous factors 

 too well understood to require mention. 



Section I4. Relation of Sire and Son in Fertility. 

 Table 14. — Correlation in Fertility between Sires and Sons. 



Constants calculated from Table 14- 



Sires' Mean Fertilitv . . . . ' 8682 ±.007041 



Sires' Standard Deviation 1361 ±.004979 



Sons' Mean Fertilitv 8441 ±.008660 



Sons' Standard Deviation 1674±. 006124 



Coefficient of Correlation 0685±. 051486 



In table 14 each pullet mate of a sire is paired with a pullet mate of his son. The 

 number of pairs concerned is 170 and the number of sires included is about the same 

 as the number of sons included. The mean fertility of the sires and their sons is 

 not significantly different, and the range in variability of sires and sons, as measured 

 by the standard deviation, is about the same. The coefficient of correlation is very 

 small and its probable error renders it negligible. The only conclusion that may be 

 drawn from tins small amount of data is that either the fertihty record of a male 's 

 mates is not a reliable index to his inherent fertilizing ability, or else degree of fer- 

 tihty is not transmitted from sire to son. 



In the next section the relation of hatchability of sire and son will be considered 

 for the same birds that were used in studying fertility. 



