Sept. IS. 191S Resemblance of Parents and Offspring of Sheep 



495 



It may also be noted that, on the whole, there is a slightly and signifi- 

 cantly larger percentage of twins among parents than among recorded 

 offspring. It must be remembered in this connection that the record of 

 any parent is repeated a number of times equal to the number of the 

 recorded offspring of the parent. Otherwise, one might be led to argue 

 in a very obvious manner that if twinning is inherited and if there is no 

 selection against twins, the percentage of twins in the offspring would 

 exceed the percentage among parents, but such an argument is not valid 

 when we repeat the parent, as above explained. 



DATA NOT INCLUDED IN FOREGOING TABLES AND CALCULATIONS 



Tables XV, XVI, and XVII exhibit data excluded from calculations 

 of statistical constants because of the abnormal proportion of twins or 

 singles recorded among the offspring of a single sire. The reasons and 

 criteria for such exclusion are given under "Repetition of sires and 

 paternal grandparents." 



Table XV. — She of litter in which offspring are horn and size of litter in which pairs 

 of parents are born {from data excluded in making Tables I and IX) 



TabIvE XVI. — Sizes of litters in which offspring and sires and paternal granddams are 

 born (from data excluded in m.aking Tables X and XI) 



97209°— 15- 



