502 



Journal of Agricultural Research 



Vol. IV, No. 6 



Table XXV(A). — Correlation between dams and inaternal grandsires with "complete 



American" pedigree 



r=o.oo7±o.oi2. 



Table XXV(B). — Percentages of dams in states I, 2, and j to correspond to states i, 2, 



and J of the grandsires 



For the "complete American " subclass (Table XXV) we are also unable 

 to assert a significant correlation between maternal grandsire and dams. 

 This fact makes it appear still a little more probable that sex is in some 

 way connected with the tendency of twins to produce twins. [Compare 

 Tables VIII (A) and XXV (A).] This point will be further treated under 

 "Analysis of data on parents and offspring separated with regard to sex." 



TABLES FOR SIRES AND OFFSPRING WITH A "COMPLETE AMERICAN" 



PEDIGREE 



While from the data of Table XXVI (A) the correlation coefficient, 

 r = o.o72±o.oii, is a little larger than for the total population, the 

 difference may be ascribed to random sampling. Just as in the "Anal- 

 ysis of data for sires and offspring" we have found mean values of an 

 index number for sires of different classes, so here we have the following 

 values for mean index numbers for animals of "complete American" 

 pedigree : 



For sires bom in singles (" complete American "), we have . i. 296±o. 012. 



For sires bom in twins ("complete American"), we have. 1.375^:0.017. 



For remaining sires born in singles, we have i. 353±o. 010. 



For remaining sires bom in twins, we have i. 384 ±0. 014. 



