offspring will be white and half blue, (6) blue
may mate with blue in which case a quarter of the offspring will be
white, a quarter black and a half blue.

[Sidenote: Guinea Pigs]

These results are the fundamental laws discovered by Mendel. But the
results are not always as clear as in the case of the Andalusian fowl.
In that case the hybrids were not like either parent, but were a new
color, blue, so that they were labeled at once and recognizable as
hybrids--but this is not generally the case. Take, for instance, guinea
pigs. What will be the result of mating an "albino" white with a black
guinea pig? Quite exactly the same principle applies as in the case of
the Andalusian fowl, but the principle is not as clear to see. All the
offspring are hybrid, but they will not be blue: they will be black.
They will look like the black parent, but they are different. The black
color predominates; i.e., black is "dominant" over white, while the
white recedes out of sight, or is "recessive." This hybrid black guinea
pig is like the hybrid blue Andalusian fowl. It is a hybrid, a
combination of white and black, but in the guinea pig the black covers
up the white so that _nothing_ in the color reveals the fact that it is
a hybrid. Now if the hybrid black offspring of these black and white
guinea pigs mate with each other, the result will follow exactly the
same Mendelian law as applied to the Andalusian fowl. But this will not
be so clear, because now we have two kinds of black instead of a black
and a blue. One child in four will be _pure bred_ black like the
grandparent and two out of the four will be _hybrid_ black. So to the
eye we shall simply have, out of four children, one white and three
black. But those three black are not all alike. One is a thoroughbred
and two are half-breeds.

But how then are we to distinguish between the one pure bred black, the
thoroughbred, and the two blacks that are hybrids so that we can be sure
which is which? The only way they can be distinguished is to wait to see
what their offspring will be in the next succeeding generations.

The one that is a thoroughbred will behave like a thoroughbred. For
instance, if mated with white they will have nothing but black children.
But if one that is hybrid black mate with one that is white, only half
of the children will be white; these white children reveal the fact that
their black parent was a half breed. Then we can put a tag on that black
parent