Breeding 437 



the immediate parents or grandparents, but which was 

 present in two of the eight grandparents. 



The appearance of this black pig, as in the case of all 

 reversions, was not an exception to the law of heredity 

 that " like begets like" ; it was rather a proof or guarantee 

 of it. Although the cross-bred pigs produced by the first 

 Yorkshire-Berkshire mating were all white, so far as their 

 breeding or hereditary qualities were concerned they 



OYork. 



York. J fO Yorkshire 



Berkshire 



fO York. 

 York. fO Yorkshire 



X Berk. 



Berkshire 



FIG. 18. Illustrating the principle of reversions. 



were as much black as white. The black did not show 

 in the bodies of these cross-bred pigs because the white 

 dominated over it. The black, in other words, was present 

 in a hidden or latent condition, illustrated in the diagram 

 by a dash below the circle. It was also present in some 

 of the pigs in the next generation, so that in the succeeding 

 generation when two of these white pigs, each with black 

 latent, were bred together some of the pigs were black. 

 What is true of color is true also of the hundreds of other 



