WHEN CHARACTERS ARE COMBINED 15 



Why, then, were these hybrids black and not blue ? Simply 

 because, with guinea pigs, black is the so-called dominant 

 color. This means that when one parent is black and the 

 other parent white, and when the two colors are therefore 



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Color Inheritance in Guinea Pigs 



Although pure-bred black guinea pigs and hybrid black guinea pigs look alike, they 

 are really different, and this difference appears in the color of their children. When 

 a pair of black guinea pigs have only black children, we know the parents are pure- 

 bred ; but when a pair of black guinea pigs have white children as well as black ones, 

 we know their parents are hybrids. Study the illustration upwards from children to 

 parents and decide which ancestors are pure, which hybrid. In doing this remember 

 that in the second generation of offspring the black one and the white one are mated 

 with pure-breds like themselves, which are not shown in the drawing. As you study 

 the illustration keep the following facts in mind : 1. Pure-bred black mated with 

 white gives black in every member of the next generation. Still each is as distinctly 

 hybrid as are the Andalusian fowls. 2. All are black and not blue, because, with 

 guinea pigs, black is the dominant, white the recessive character. 3. Whenever a 

 white guinea pig appears as the offspring of two black guinea pigs, we know that the 

 parents were hybrids. (Find them in the illustration.) For this reason we can never 

 tell whether a black guinea pig is pure or hybrid until we have seen its offspring. 

 4. Whenever all the children of two black guinea pigs are black, we know that at 

 least one of the parents was pure. (Find them in the drawing.) 5. Whenever a white 

 guinea pig mates with a white one, all the offspring are sure to be white. Compare 

 this illustration with that of the Andalusian fowls. Note the differences 



to be passed on by inheritance to later generations of guinea 

 pigs, the black dominates.in the immediate next generation. 

 The white color, on the other hand, is recessive ; that is, 

 it recedes from sight and does not appear in any member 



