Hence, the harvest of the variety may be
rendered pure or nearly so, while the harvest of the species will retain
the seeds of the hybrids. Moreover it will contain seeds originated by
the spontaneous but numerous crosses of the true plants with the
sparsely intermingled hybrids.
This brings us to the question, as to what will be the visible
consequences of the occurrence of such invisible hybrids in the
following generation. In opposition to the direct effects just
described, we may call them indirect. To judge of their influence, we
must know how hybrid seeds of the first generation behave.
In one of our lectures we will deal with the laws that show the
numerical relations known as the laws of Mendel. But for our present
purpose, these numerical relations are only of subordinate importance.
What interests us here is the fact that hybrids of varieties do not
remain constant in the second generation but usually split as it is
said, remaining hybrid only in part of their offspring, the other
portion returning to the parental types. This however, will show itself
only in those individuals [211] which reassume the character of the
varietal parent, all the others apparently remaining true to the type of
the species. Now it is easy to foresee what must happen in the second
generation if the first generation after the cross is supposed to be
kept free from new vicinistic influences, or from crosses with
neighboring varieties.
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