No. 557] INHERITANCE OF MAMM2E IN SWINE 265 



Inheritance of the Two Forms of Variation. — The 

 " triangles ' ' show a marked degree of inheritance. 

 Neither boar carried the triangular pattern somatically, 

 but the offspring of the two were summarized separately 

 to see if any difference developed in the offspring. Both 

 boars possessed the " suppressed nipple" type, and, as 

 might be expected, show little difference in breeding. 



Pigs by Old Boar 







triangle 







Sows vith triangle 



Sows with suppressed nipple. . . 



No. 

 Per cent, 



No. . 

 Per cent. 



No. 

 Per rent. 



30.00 

 2 



4.7 



20.00 

 33.3 

 22.2 



28 



26°° 





It is evident that a distinctly higher proportion of 

 " triangles" appears in the pigs from sows of the same 

 type. Also a distinctly greater percentage of pigs with 

 the suppressed nipple comes from sows of the suppressed- 

 nipple type, but the difference between the breeding char- 

 acter of the three classes of sows is not so marked with 

 this variation, probably because the boar supplies the 

 latter pattern with each mating. 



Pigs by Young Boar. 



Combining the two tables, there appears a result which 

 may be more significant than in either when separate. In 

 this table in the cases where a pig possesses both varia- 

 tions, he is listed twice, so that the percentage runs 

 slightly over one hundred. There is one duplication from 

 sows with the triangle and four duplications in the off- 

 spring of the 1 ' normal" sows. 



