16 THE NEXT GENERATION 



of that next generation. These two words, dominant and 

 recessive, are to be remembered, because, as we shall see 

 later, they help us understand why one character and not 

 another makes its appearance in succeeding generations. 



As we already know, with Andalusian fowls neither black 

 nor white is either dominant or recessive. As a result, when 

 the two are mated, the color of the next generation is neither 

 black nor white, but a mixture of the two, and every member 

 of the young family is blue. 



With guinea pigs, however, black dominates in such high- 

 handed fashion that white is crowded entirely out of sight in 

 the next family of descendants. "White is therefore called the 

 recessive color. Even hybrids among them are black. Study 

 the illustration to see what occurs in each successive generation. 

 Notice that the children of black hybrid guinea pigs are 

 of three sorts, even as are the children of blue hybrid Anda- 

 lusian fowls. 



(One is pure-bred white, like its white grandparent. 

 One is pure-bred black, like its black grandparent. 

 Two are hybrid black, like the parents. 



It is evident.then, that nature does not always label children 

 so clearly as Andalusian fowls are labeled. Nevertheless, in 

 both cases the same great laws hold true for ancestors and 

 descendants alike. 



Now go a step further. Dr. Castle tells us that color is 

 not the only character which moves along in definite fashion, 

 by definite laws. He says that when he mates a rough- 

 coated guinea pig with one that has a smooth coat, all the 

 little guinea pigs of the next generation, whether they are 

 white or black, brown or yellow, have rough coats ; hot one 

 among them is smooth-coated. This means that rough coat is 

 the dominant character and smooth coat the recessive character. 



