discussion whether recent forms are more highly developed than ancient.
I will not here enter on this subject, for naturalists have not as yet
defined to each other s satisfaction what is meant by high and low
forms. But in one particular sense the
more recent forms must, on my theory, be higher than the more ancient;
for each new species is formed by having had some advantage in the
struggle for life over other and preceding forms. If under a nearly
similar climate, the eocene inhabitants of one quarter of the world
were put into competition with the existing inhabitants of the same or
some other quarter, the eocene fauna or flora would certainly be beaten
and exterminated; as would a secondary fauna by an eocene, and a
pal ozoic fauna by a secondary fauna. I do not doubt that this process
of improvement has affected in a marked and sensible manner the
organisation of the more recent and victorious forms of life, in
comparison with the ancient and beaten forms; but I can see no way of
testing this sort of progress. Crustaceans, for instance, not the
highest in their own class, may have beaten the highest molluscs. From
the extraordinary manner in which European productions have recently
spread over New Zealand, and have seized on places which must have been
previously occupied, we may believe, if all the animals and plants of
Great Britain were set free in New Zealand, that in the course of time
a multitude of British forms would become thoroughly naturalized there,
and would exterminate many of the natives. On the other hand, from what
we see now occurring in New Zealand, and from hardly a single
inhabitant of the southern hemisphere having become wild in any part of
Europe, we may doubt, if all the productions of New Zealand were set
free in Great Britain, whether any considerable number would be enabled
to seize on places now occupied by our native plants and animals. Under
this point of view, the productions of Great Britain may be said to be
higher than those of New Zealand. Yet the most skilful naturalist from
an examination of the species
of the two countries could not have foreseen this result.
Agassiz insists that ancient animals resemble to a certain extent the
embryos of recent animals of the same classes; or that the geological
succession of extinct forms is in some degree parallel to the
embryological development of recent forms. I must follow Pictet and
Huxley in thinking that the truth of this doctrine is very far from
proved. Yet I fully expect to see it hereafter confirmed, at least in
regard to subordinate groups, which have branched off from each other
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