62 



The Journal of Heredity 



A CROSSBRED FROM THE BERKSHIRE X DUROC-JERSEY CROSS 



This boar was the father of the second and backcross generations. Compare it with its parent 

 breeds shown in Figs. 8 and 9 and note its color, erect ears and intermediate face shape. (Fig. 10.) 



White: Tlu-rt" are at least three kinds of 

 white which are genetically distinct. 

 Self white is dominant over all other 

 colors with which it has been crossed 

 and is probably dependent upon 

 only one factor. White belt (as seen 

 in the American Hain|)sliire or in 

 the ("leniian Hanoxi-rian swine) is 

 usually dominant but must depend 

 ujM)!! at least two factors since 

 belted offspring sometimes result 

 from non-belted parents. The white 

 which is best illustrated in the "six 

 white points" of the Berkshire or 

 Folanfl-China, si-ems to be an ex- 

 tremely diluted red or the absence of 

 all shades of reel. Tlu- author has 

 foimd no rec>)rd of true albinism in 

 swim-. 



Black: There are certainly two and \ ery 

 pn)bably three kinds of black. Self 



black (as in the Knglish Large Black 

 swine) is reported dominant toTam- 

 worth red. The black which is asso- 

 ciated with the white belt in the 

 American Hampshire is dominant 

 to Duroc-Jersey red and depends 

 upon a single factor. There is no 

 e\idence as to whether these two 

 kinds of black are genetically dis- 

 tinct, or the latter is merely self 

 black plus the additional unknown 

 factors for white belt. The black of 

 the Berkshire and Poland-China is 

 certainly distinct from both the pre- 

 ceding kinds since it always breaks 

 uji, when crossed with red, into nu- 

 merous l)la<"k spots scattered over a 

 lighter backgroimd, usually red or 

 sand\- but sometimes white.* This 

 l)lack, as will appe.ir from the results 

 of this ixiuriment, is caused by a 



• Sever.son, B. O. 1917. Color Inhrritancc in Swim-. Jocrnai. ok Mkridity, Vol. 8, p. .S79. 



