14 THE NEXT GENERATION 



or rosettes ; others, both the long-haired and the short-haired, 

 had coats smooth like silk. Some had fur so short that each 

 separate hair stayed in place without being brushed ; others 

 had hair so long that it could be combed and parted and 

 brushed from side to side. Indeed, the length of hair for a 

 full-grown guinea pig runs all the way from less than two 

 inches on some to over six inches on others. 



But whatever the character of the fur, whether long or 

 short, black or white, rough or smooth, Dr. Castle found that 

 each one of these characters was transmitted from ancestor 

 to descendant in accordance with definite laws, and that 

 the laws themselves are quite like those which control the 

 descendants of Andalusian fowls. 



At first sight this seems to be hardly true. Take, for exam- 

 ple, his black guinea pigs mated with white albino 1 guinea 

 pigs. Judging by Andalusian fowls, we should expect to see 

 a row of small blue guinea pigs in the next generation. But 

 study the diagram and see what actually happened. One 

 parent was pure-bred black, the other was pure-bred albino 

 white, yet every child of theirs was as black as its black 

 parent. Not a blue one or a white one was found anywhere 

 among them. It looked as if each had inherited from its 

 black parent alone as if the white parent had not been 

 taken into account at all. Still we know that every guinea 

 pig in the row was bound to be hybrid ; we know there was 

 no escape for them, because, one and all, they were the 

 children of two different kinds of pure-bred parents. 



2 "An albino is an animal with unpigmented eyes and with little or no 

 pigment in its coat." Castle. The eyes of an albino are pink because there 

 is no pigment in the iris. The color of the blood vessels therefore shines 

 through it. Albino guinea pigs always have pink eyes. There are white 

 guinea pigs with black eyes. These are not albino. In this chapter it is 

 the albino white that are mentioned. The other white ones are not pure-bred. 



