conceive it to pass from the
one to the other state by natural selection. The battle of life the
ducks will have to fight will increase in peril continually as they
cease (with the change of their bill) to be ducks, and attain a
_maximum_ of danger in the condition in which they begin to be gulls;
and ages must elapse and whole generations must perish, and countless
generations of the one species be created and sacrificed, to arrive at
one single pair of the other."

In this passage the theory of natural selection is so absurdly
misrepresented that it would be amusing, did we not consider the
misleading effect likely to be produced by this kind of teaching in so
popular a journal. It is assumed that the duck and the gull are
essential parts of nature, each well fitted for its place, and that if
one had been produced from the other by a gradual metamorphosis, the
intermediate forms would have been useless, unmeaning, and unfitted for
any place, in the system of the universe. Now, this idea can only exist
in a mind ignorant of the very foundation and essence of the theory of
natural selection, which is, the preservation of _useful_ variations
only, or, as has been well expressed, in other words, the "survival of
the fittest." Every intermediate form which could possibly have arisen
during the transition from the duck to the gull, so far from having an
unusually severe battle to fight for existence, or incurring any
"_maximum_ of danger," would necessarily have been as accurately
adjusted to the rest of nature, and as well fitted to maintain and to
enjoy its existence, as the duck or the gull actually are. If it were
not so, it never could have been produced under the law of natural
selection.

_Intermediate or generalized Forms of extinct Animals, an indication of
Transmutation or Development._

The misconception of this writer illustrates another point very
frequently overlooked. It is an essential part of Mr. Darwin's theory,
that one existing animal has not been derived from any other existing
animal, but that both are the descendants of a common ancestor, which
was at once different from either, but, in essential characters,
intermediate between them both. The illustration of the duck and the
gull is therefore misleading; one of these birds has not been derived
from the other, but both from a common ancestor. This is not a mere
supposition invented to support the theory of natural selection, but is
founded on a