66 



The Journal of Heredity 



THE SECOND GENERATION PIG WHICH SHOWED THE MOST BLACK (BERKSHIRE X 



DUROC- JERSEY CROSS j 



The first generation was composed wholly of red pigs with black spots. There was much varia- 

 tion in the second generation of which the case illustrated above is an extreme example. (Fig. 15.) 



Ten pigs were produced in the Fi of 

 the Berkshire XTamworth cross. Kight 

 were red with one or more small black 

 spots and two were self red. The spots 

 were very small and much fewer than in 

 the pigs from the Berkshire XDuroc- 

 Jersey cross. One had but a single 

 black spot and it seems possible that 

 the restriction factors for black are 

 so strong in the Tamworth breed that 

 the two self red pigs are merely somatic 

 variations in the amount of l)lack and 

 not genetically different from their lit- 

 ter mates. 



In the BerkshireXHuroc-Jersey cross 

 there were produced an Fi generation 

 of twenty-nine pigs, an F2 generation of 

 one hundred fifty-one pigs, a back- 

 cross generation (Fid" X l3uroc9) of 

 thirty-five pigs, one F3 litter of eleven 

 pigs, and a litter (Ficf X F29) of five 

 pigs. The I''i i)igs were all red with 

 black spots, but the red became lighter 

 in color as they grew older. The colors 



of the F2 and backcross pigs are given in 

 Table II. 



Table II 



The red and sandy are quite distinct 

 at birth but as the pigs grow older they 

 may become darker or lighter until at 

 maturity- almost all shades of red are 

 represented. Taking the classification 

 at birth, it appears that black con- 



