"
"
"
Aab
138
"
"
"
AaBb.
The whole of the forms may be classed into three essentially different groups. The first embraces those with the signs AB, Ab, aB, and ab: they possess only constant characters and do not vary again in the next generation. Each of these forms is represented on the average thirty-three times. The second group embraces the signs ABb, aBb, AaB, Aab: these are constant in one character and hybrid in another, and vary in the next generation only as regards the hybrid character. Each of these appears on an average sixty-five times. The form AaBb occurs 138 times: it is hybrid in both characters, and behaves exactly as do the hybrids from which it is derived.