Numerous other cases exhibit smaller numbers of elementary units within
a systematic species; in fact purely uniform species seem to be
relatively rare. But with small numbers there are of course no
indications to be expected concerning their common origin or the
starting point of their distribution.
It is manifest that these experiences with wild species must find a
parallel among cultivated plants. Of course cultivated plants were
originally wild and must have come under the general law. Hence we may
conclude that when first observed and taken up by man, they must already
have consisted of sundry elementary subspecies. And we may confidently
assert that some must have been rich and others poor in such types.
Granting this state of things as the only probable one, we can easily
imagine what must have been the consequences. If a wild species had been
taken into cultivation only once, the cultivated form would have been a
single elementary [65] type. But it is not very likely that such
partiality would occur often. The conception that different tribes at
different times and in distant countries would have used the wild plants
of their native regions seems far more natural than that all should have
obtained plants for cultivation from the same source or locality. If
this theory may be relied upon, the origin of many of the more widely
cultivated agricultural plants must have been multiple, and the number
of the original elementary species of the cultivated types must have
been so much the larger, the more widely distributed and variable the
plants under consideration were before the first period of cultivation.
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