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THE AMERICAN NATURALIST [Vol.L 



Moore 25 on fertility in man and fecundity in race horses in that 

 they deal with the number of young produced at a single birth 

 instead of with the total young produced during the reproductive 

 period or the ratio of the number of young actually born to the 

 number which might have been produced under the circui 



For Poland China sows Rommel 26 and Rommel and Phillips 

 found values of the correlation between the size of litters 

 which dam was farrowed and size of litters produced by daugh- 

 ters ranging from .1088 to .0032, the values decreasing with 

 moderate regularity as the daughters became older. For all 

 ages they find the correlation r = .0601, and conclude that fer- 

 tility is slightly but definitely inherited. 



George (fide Wentworth and Aubel, loc. cit.) worked out foui 

 supplementary series in Poland China swine with the results : 

 Daughter and dam, r = .0615 ± .0390, 



Dam and grandam, r=.1147 ± .0343, 



Daughter and maternal grandam, r = .0025 ± .0392, 

 Daughter and paternal grandam, r=.0508 ± .0392. 

 All of these values are positive, but they are very small and no 

 one of them may be considered statistically trustworthy in com- 

 parison with its probable error. 



Weldon and Pearson 28 give a series of six relationships, both 

 parental and grandparental, for size of litter in mice, with the 

 result that no correlation whatever could be demonstrated. 



Wentworth and Aubel 29 have considered the possibility of the 

 segregation of litter size in the two first descendant generations 

 of matmgs between boars and sows farrowed in litters of various 

 sizes by determining the standard deviation of the number per 

 litter m the so-called F t and F 2 generations. Let I be the num- 



- rearson, K., A. Lee and L. Brs 

 192: 2;!7-330, 1899. 



■ Size < 



