Darwinism | Page 5

birds,
the rook (Corvus frugilegus) and the crow (Corvus corone). These are
distinct species, because, in the first place, they always differ from each
other in certain slight peculiarities of structure, form, and habits, and, in
the second place, because rooks always produce rooks, and crows
produce crows, and they do not interbreed. It was therefore concluded
that all the rooks in the world had descended from a single pair of rooks,
and the crows in like manner from a single pair of crows, while it was
considered impossible that crows could have descended from rooks or
vice versâ. The "origin" of the first pair of each kind was a mystery.
Similar remarks may be applied to our two common plants, the sweet
violet (Viola odorata) and the dog violet (Viola canina). These also
produce their like and never produce each other or intermingle, and
they were therefore each supposed to have sprung from a single
individual whose "origin" was unknown. But besides the crow and the
rook there are about thirty other kinds of birds in various parts of the
world, all so much like our species that they receive the common name
of crows; and some of them differ less from each other than does our
crow from our rook. These are all species of the genus Corvus, and
were therefore believed to have been always as distinct as they are now,
neither more nor less, and to have each descended from one pair of
ancestral crows of the same identical species, which themselves had an
unknown "origin." Of violets there are more than a hundred different
kinds in various parts of the world, all differing very slightly from each
other and forming distinct species of the genus Viola. But, as these also
each produce their like and do not intermingle, it was believed that
every one of them had always been as distinct from all the others as it
is now, that all the individuals of each kind had descended from one
ancestor, but that the "origin" of these hundred slightly differing
ancestors was unknown. In the words of Sir John Herschel, quoted by
Mr. Darwin, the origin of such species was "the mystery of mysteries."

The Early Transmutationists.
A few great naturalists, struck by the very slight difference between
many of these species, and the numerous links that exist between the
most different forms of animals and plants, and also observing that a
great many species do vary considerably in their forms, colours, and
habits, conceived the idea that they might be all produced one from the
other. The most eminent of these writers was a great French naturalist,
Lamarck, who published an elaborate work, the Philosophie
Zoologique, in which he endeavoured to prove that all animals
whatever are descended from other species of animals. He attributed
the change of species chiefly to the effect of changes in the conditions
of life--such as climate, food, etc.--and especially to the desires and
efforts of the animals themselves to improve their condition, leading to
a modification of form or size in certain parts, owing to the well-known
physiological law that all organs are strengthened by constant use,
while they are weakened or even completely lost by disuse. The
arguments of Lamarck did not, however, satisfy naturalists, and though
a few adopted the view that closely allied species had descended from
each other, the general belief of the educated public was, that each
species was a "special creation" quite independent of all others; while
the great body of naturalists equally held, that the change from one
species to another by any known law or cause was impossible, and that
the "origin of species" was an unsolved and probably insoluble problem.
The only other important work dealing with the question was the
celebrated _Vestiges of Creation_, published anonymously, but now
acknowledged to have been written by the late Robert Chambers. In
this work the action of general laws was traced throughout the universe
as a system of growth and development, and it was argued that the
various species of animals and plants had been produced in orderly
succession from each other by the action of unknown laws of
development aided by the action of external conditions. Although this
work had a considerable effect in influencing public opinion as to the
extreme improbability of the doctrine of the independent "special
creation" of each species, it had little effect upon naturalists, because it
made no attempt to grapple with the problem in detail, or to show in
any single case how the allied species of a genus could have arisen, and

have preserved their numerous slight and apparently purposeless
differences from each other. No clue whatever was afforded to a law
which should produce from any one species one or more slightly
differing but