16 



HELEN DEAN KING 



TABLE 7 



Showing, by generation groups, the sex ratios in the inbred and in the half-inbred 

 litters of the B series {female line) 



In the B series, as in .the A series, there was a wide range of 

 variation in the sex ratios of the htters produced in the first seven 

 generations (table 5) . When the data were combined in genera- 

 tion groups (table 7), the sex ratio in the 136 inbred litters (109 

 d^ : 100 ? ) was found to be above the norm, while that in the 

 half-inbred litters (98.3 d^ : 100 9 ) was below the norm. These 

 two ratios so nearly balance each other that for the total of 229 

 litters the sex ratio was 104 . 2 cf : 100 9 , or less than 1 point be- 

 low the norm : in the corresponding litters of the A series the sex 

 ratio was 8 points above the norm (113.2 d^ : 100 9). On com- 

 bining the records for the first seven generations of the two in- 

 bred series (A, B), it was found that the total of 479 litters gave a 

 sex ratio of 108.6 d" : 100 9 . While this ratio is over 3 points 

 above the norm, it is not sufficiently high to warrant the con- 

 clusion that the normal sex ratio was changed through inbreeding, 

 particularly as the ratio was due in great part to an unusual ex- 

 cess of males in the hal '-inbred litters of the A series (table 4). 



