Darwinism | Page 6

yet permanently distinct species, nor was any reason given
why such slight yet constant differences should exist at all.
Scientific Opinion before Darwin.
In order to show how little effect these writers had upon the public
mind, I will quote a few passages from the writings of Sir Charles Lyell,
as representing the opinions of the most advanced thinkers in the period
immediately preceding that of Darwin's work. When recapitulating the
facts and arguments in favour of the invariability and permanence of
species, he says: "The entire variation from the original type which any
given kind of change can produce may usually be effected in a brief
period of time, after which no further deviation can be obtained by
continuing to alter the circumstances, though ever so gradually,
indefinite divergence either in the way of improvement or deterioration
being prevented, and the least possible excess beyond the defined limits
being fatal to the existence of the individual." In another place he
maintains that "varieties of some species may differ more than other
species do from each other without shaking our confidence in the
reality of species." He further adduces certain facts in geology as being,
in his opinion, "fatal to the theory of progressive development," and he
explains the fact that there are so often distinct species in countries of
similar climate and vegetation by "special creations" in each country;
and these conclusions were arrived at after a careful study of Lamarck's
work, a full abstract of which is given in the earlier editions of the
Principles of Geology.[2]
Professor Agassiz, one of the greatest naturalists of the last generation,
went even further, and maintained not only that each species was
specially created, but that it was created in the proportions and in the
localities in which we now find it to exist. The following extract from
his very instructive book on Lake Superior explains this view: "There
are in animals peculiar adaptations which are characteristic of their
species, and which cannot be supposed to have arisen from subordinate

influences. Those which live in shoals cannot be supposed to have been
created in single pairs. Those which are made to be the food of others
cannot have been created in the same proportions as those which live
upon them. Those which are everywhere found in innumerable
specimens must have been introduced in numbers capable of
maintaining their normal proportions to those which live isolated and
are comparatively and constantly fewer. For we know that this harmony
in the numerical proportions between animals is one of the great laws
of nature. The circumstance that species occur within definite limits
where no obstacles prevent their wider distribution leads to the further
inference that these limits were assigned to them from the beginning,
and so we should come to the final conclusion that the order which
prevails throughout nature is intentional, that it is regulated by the
limits marked out on the first day of creation, and that it has been
maintained unchanged through ages with no other modifications than
those which the higher intellectual powers of man enable him to
impose on some few animals more closely connected with him."[3]
These opinions of some of the most eminent and influential writers of
the pre-Darwinian age seem to us, now, either altogether obsolete or
positively absurd; but they nevertheless exhibit the mental condition of
even the most advanced section of scientific men on the problem of the
nature and origin of species. They render it clear that, notwithstanding
the vast knowledge and ingenious reasoning of Lamarck, and the more
general exposition of the subject by the author of the Vestiges of
Creation, the first step had not been taken towards a satisfactory
explanation of the derivation of any one species from any other. Such
eminent naturalists as Geoffroy Saint Hilaire, Dean Herbert, Professor
Grant, Von Buch, and some others, had expressed their belief that
species arose as simple varieties, and that the species of each genus
were all descended from a common ancestor; but none of them gave a
clue as to the law or the method by which the change had been effected.
This was still "the great mystery." As to the further question--how far
this common descent could be carried; whether distinct families, such
as crows and thrushes, could possibly have descended from each other;
or, whether all birds, including such widely distinct types as wrens,
eagles, ostriches, and ducks, could all be the modified descendants of a

common ancestor; or, still further, whether mammalia, birds, reptiles,
and fishes, could all have had a common origin;--these questions had
hardly come up for discussion at all, for it was felt that, while the very
first step along the road of "transmutation of species" (as it was then
called) had not been made, it was