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