Two of them have reassumed the stability of their original
grandparents, and the third has retained the instability of the hybrid
parents.
The question now arises as to the numerical relation of these groups.
Our experiments gave the following results: [293]
Cross 1. Generation 2. Generation 3. Generation
Mephisto 4- 100% Mephisto
| /
| /
| 77.5 % Dom.
| / \
> --All Mephisto \
| \ 9- all hybrids with 83-68%
| 22.5 % Rec. dominants and 17-32%
| recessives. 100% Danebrog.
Danebrog
Examining these figures we find one-fourth of constant recessives, as
has already been said, further one-fourth of constant dominants, and the
rest or one half as unstable hybrids. Both of the pure groups have
therefore reappeared [293] in the same numbers. Calling A the specimens
with the pure active mark, L those with the latent mark, and H the
hybrids, these proportions may be expressed as follows:
1A+2H+1L.
This simple law for the constitution of the second generation of
varietal hybrids with a single differentiating mark in their parents is
called the law of Mendel.
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