No. 598] SHORTER ARTICLES AND DISCUSSION 633 



ber of pigs in the litter in which an individual was farrowed, d 

 the number of pigs in the litter in which its dam was farrowed, 

 and 8 and D the numbers in the litters in which the grandsire 

 and grandam were farrowed. Then, the authors reason, if fer- 

 tility be due to factors which differ in the grandsire, 8, and the 

 grandam, D, and if Mendelian segregation occurs in the fashion 

 assumed by several of these who have worked on quantitative 

 characters, one should expect the mean value of the standard 

 deviation of litter size in cases in which D and 8 differ widely to 

 be higher than the mean value in cases in which they are closely 

 similar. There is no conclusive evidence of such greater segre- 

 gation in the F 2 from dissimilar grandparents. 



Now the data published by Wentworth and Anbcl permit the 

 consideration of several additional questions of considerable in- 

 terest in connection with the problem of the inheritance of fer- 

 tility. Thus from the mean litter sizes in their Table II and the 

 distributions of litter size in the three generations in their Table 

 IV, it is quite possible to calculate approximately 30 correct cor- 

 relations for the relationship between size of litter in different 

 generations. Thus the formula : 



where the bars denote the means of the y (descendant) litters 

 associated with particular, x, classes of ascendant litters, leads 

 to the values : 31 



r* - .120 ± .022, r m = .100 ± .022. 



Superficially considered, these values seem in excellent agree- 

 ment with those published by Rommel and others, but the fact 

 that r M has a value which is possibly significant statistically, 

 should at once arouse suspicion, for surely there is no genetic 

 reason (excepting possibly non-viability of sperm or the produc- 

 tion of duplicate twins through an influence of the sperm upon 

 the egg) why there should be a correlation between the size of the 

 litter in which a boar was farrowed and the size of litter in which 

 his daughter was farrowed. Mistrust is heightened by the fact 



so Unfortunately there are inconsistencies in these tables which show the 



