For my crosses I have taken the dark-centered "Mephisto" and the
"Danebrog," or Danish flag, with a white cross on a red field. The
second year the hybrids were all true to the type of "Mephisto." From
the seeds of each artificially self-fertilized capsule, one-fourth
(22.5%) [292] in each instance reverted to the varietal mark of the
white cross, and three-fourths (77.5%) retained the dark heart. Once
more the flowers were self-pollinated and the visits of insects
excluded. The recessives now gave only recessives, and hence we may
conclude that the varietal marks had returned to stability. The dark
hearted or dominants behaved in two different ways. Some of them
remained true to their type, all their offspring being dark-hearted.
Evidently they had returned to the parent with the active mark, and had
reassumed this type as purely as the recessives had reached theirs. But
others kept true to the hybrid character of the former generation,
repeating in their progeny exactly the same mixture as their parents,
the hybrids of the first generation, had given.
This third generation therefore gives evidence, that the second though
apparently showing only two types, really consists of three different
groups. 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.
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