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Darwin, Charles, 1809-1882

"The Origin of Species by means of Natural Selection, 6th Edition"

As soon as
the three Orchidean forms, Monachanthus, Myanthus, and Catasetum, which had
previously been ranked as three distinct genera, were known to be sometimes
produced on the same plant, they were immediately considered as varieties;
and now I have been able to show that they are the male, female, and
hermaphrodite forms of the same species. The naturalist includes as one
species the various larval stages of the same individual, however much they
may differ from each other and from the adult; as well as the so-called
alternate generations of Steenstrup, which can only in a technical sense be
considered as the same individual. He includes monsters and varieties, not
from their partial resemblance to the parent-form, but because they are
descended from it.
As descent has universally been used in classing together the individuals
of the same species, though the males and females and larvae are sometimes
extremely different; and as it has been used in classing varieties which
have undergone a certain, and sometimes a considerable amount of
modification, may not this same element of descent have been unconsciously
used in grouping species under genera, and genera under higher groups, all
under the so-called natural system? I believe it has been unconsciously
used; and thus only can I understand the several rules and guides which
have been followed by our best systematists.


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