No. 557] INHERITANCE OF MAMMJE IN SWINE 273 



even overlap. In the pigs by the young boar the corre- 

 lation between the same sides of sow and offspring ex- 

 ceeds that of the opposite sides, but in the offspring of 

 the old boar the left side of the pig is more closely cor- 

 related to either side of the mother than is the right side 

 of the pig. These contradictions lead the writer to be- 

 lieve that the inheritance is not lateral. 



All of the offspring were tabulated as to number of 

 pairs against their dams and the correlation was deter- 

 mined. The coefficient is .1994 ± .028, large enough to 

 show some inheritance. As the animals included here 

 possess the two common types of variation, or were from 

 dams possessing those types, a second table was prepared 

 of pigs with symmetrical pairs from sows of the same 

 type. A larger coefficient resulted, .3588 ± .039, but even 

 this is not satisfactory, as the boars possess the sup- 

 pressed nipple, and of course, the offspring represent a 

 selected group, although not selected from a standpoint 

 that should favor the correlation. 



Another method of tabulating may show the inheritance 

 more graphically. The boars have six pairs, with one 

 mamma suppressed. 



6 5.76 5.48 



7 5.90 5.65 



There is a distinct increase in the means of the off- 

 spring as the number of pairs increases in the parent. 

 The mating of the boars to the sows with the following 

 number of mammae is interesting : 



This corroborates the results above. 

 The foregoing tables lead the writer to believe that the 

 method of inheritance is by the pair rather than the side. 



