We can
clearly see why the remains of an intermediate formation are intermediate
in character.
The inhabitants of the world at each successive period in its history have
beaten their predecessors in the race for life, and are, in so far, higher
in the scale, and their structure has generally become more specialised;
and this may account for the common belief held by so many
palaeontologists, that organisation on the whole has progressed. Extinct
and ancient animals resemble to a certain extent the embryos of the more
recent animals belonging to the same classes, and this wonderful fact
receives a simple explanation according to our views. The succession of
the same types of structure within the same areas during the later
geological periods ceases to be mysterious, and is intelligible on the
principle of inheritance.
If, then, the geological record be as imperfect as many believe, and it may
at least be asserted that the record cannot be proved to be much more
perfect, the main objections to the theory of natural selection are greatly
diminished or disappear. On the other hand, all the chief laws of
palaeontology plainly proclaim, as it seems to me, that species have been
produced by ordinary generation: old forms having been supplanted by new
and improved forms of life, the products of variation and the survival of
the fittest.
CHAPTER XII.
GEOGRAPHICAL DISTRIBUTION.
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