| → of a genus ever 1861 1866 1869 1872 |
| are 1859 1860 |
|
| → the other species becoming utterly extinct and leaving no modified progeny. 1861 1866 1869 1872 |
| at any one period; and all changes are slowly effected. 1859 1860 |
|
|
should remember that we have no right to expect (excepting in rare cases) to discover
directly
connecting links between them, but only between each and some extinct and supplanted form. Even on a wide area, which has during a long period remained continuous, and of which the
and other conditions of life change insensibly in
from a district occupied by one species into another district occupied by a closely allied species, we have no just right to expect often to find intermediate varieties in the intermediate
For we have reason to believe that only a few species
→of a genus ever
→the other species becoming utterly extinct and leaving no modified progeny. Of the species which do change, only a few within the same country change at the same time; and all modifications are slowly effected. I have also shown that the intermediate varieties which
at first
in the intermediate zones,
be liable to be supplanted by the allied forms on either hand;
the latter, from existing in greater numbers,
generally be modified and improved at a quicker rate than the intermediate varieties, which
in lesser numbers; so that the intermediate varieties
in the long run, be supplanted and exterminated. |
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| On this doctrine of the extermination of an infinitude of connecting links, between the living and extinct inhabitants of the world, and at each successive period between the extinct and still older species, why is not every geological formation charged with such links? Why does not every collection of fossil remains afford plain evidence of the
and mutation of the forms of life? Although geological research has undoubtedly revealed the former existence of many links, bringing numerous forms of life much closer together, it does not yield the infinitely many fine
|
