No. 611] FERTILITY IN SOUTHDOWN SHEEP 675 



TABLE XVI 



1 • 1.3340 ±.00229 ! .48658 20,668 



2 1.3308=t .00403 j .47677 j 6,382 



The difference between singles and twins is .0032 

 + .0463 ; between singles and triplets, .0978 + .02916 ; and 

 between twins and triplets, .1010 + .02936. 



TABLE XVII 

 Breeding Performance of Females from Table XV 



The difference between singles and twins is found to be 

 0.0170 + 0.00422; between singles and triplets, 0.0854 

 + 0.02545; and between twins and triplets, 0.0684 

 + 0.02556. Several of the differences in Tables XV and 

 XVI verge on significance, being at least three times the 

 probable error. 



Relative Influence of Male and Female in 

 Grandparents 

 From the study of the relative influence of the sires 

 and dams on the progeny it would seem fruitless from 

 biometric grounds to look for transmission through one 

 sex more than the other. Yet logically it would seem that 

 the grandsire and grandam on the dam's side would have 

 a more potent effect on the birth number from the dam 

 than would the paternal grandparents. Studies of this 

 sort are available from the pedigrees. Perhaps the first 

 concern is to determine the relation of the birth rank of 

 the grandparents to that of the progeny. Table XVIII 

 presents this information. 



