THE 



AMERICAN NATURALIST 



Vol. XLVII May, 1913 No. 557 



INHERITANCE OF MAMM^J IN DUBOC JERSEY 

 SWINE 



PROFESSOR EDW. N. WENTWORTH 



The relative fixity of character and definite methods of 

 variation in the mammae of swine make them a fruitful 

 field for inheritance studies. The observations incorpo- 

 rated into this paper were made upon swine used in a 

 feeding experiment at the Iowa State College. There 

 were fifty-seven grade Duroc Jersey sows and five hun- 

 dred and ten pigs of 1912 farrowing included in the in- 

 vestigation. 1 



The sows may be divided into two groups, one of forty 

 two-year-old animals and the other of their yearling 

 daughters, seventeen in number. In all, there are three 

 generations for comparative study, a rare combination 

 in such numbers among ordinary slow-breeding farm ani- 

 mals. There were two boars in use in the experiment, 

 one a yearling, the other a two-year-old, both closely 

 related as ordinary pedigree breeding is considered. 

 From the standpoint of mammae pattern, the boars were 



'The writer wishes to make acknowledgments to Professor John M. 

 Evvard, of the Iowa Station, for the facilities he put at the writer's dis- 

 posal and to Mr. A. E. Chappel, a senior student, for great assistance in the 

 collection of data. But most of all, acknowledgments must be made to 

 Dr. Castle, of Harvard University, for his assistance in the study of the 



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