species.
In In 1869 1872 | When 1859 1860 1861 1866 |
either case
....... 1869 1872 | occurs, 1859 1860 1861 1866 |
it would be easy for natural selection to
adapt adapt 1869 1872 | fit 1859 1860 1861 1866 |
the
structure of the animal to structure of the animal to 1869 1872 |
animal, by some modification of its structure, for 1859 1860 1861 1866 |
its changed habits, or exclusively
to to 1869 1872 | for 1859 1860 1861 1866 |
one of its several
....... 1869 1872 | different 1859 1860 1861 1866 |
habits.
It is, however, It is, however, 1869 1872 |
But it is 1859 1860 1861 1866 |
difficult to
decide, decide, 1869 1872 | tell, 1859 1860 1861 1866 |
and immaterial for us, whether habits generally change first and structure afterwards; or whether slight modifications of structure lead to changed habits; both probably often
occurring occurring 1869 1872 | change 1859 1860 1861 1866 |
almost simultaneously. Of cases of changed habits it will suffice merely to allude to that of the many British insects which now feed on exotic plants, or exclusively on artificial substances. Of diversified habits innumerable instances could be given: I have often watched a tyrant flycatcher (Saurophagus sulphuratus) in South America, hovering over one spot and then proceeding to another, like a kestrel, and at other times standing stationary on the margin of water, and then dashing
into it like into it like 1866 1869 1872 |
like 1859 1860 1861 |
a kingfisher at a fish. In our own country the larger titmouse (Parus major) may be seen climbing branches, almost like a creeper; it
sometimes, sometimes, 1869 1872 | often, 1859 1860 1861 1866 |
like a shrike, kills small birds by blows on the head; and I have many times seen and heard it hammering the seeds of the yew on a branch, and thus breaking them like a nuthatch. In North America the black bear was seen by Hearne swimming for hours with widely open mouth, thus catching,
almost like almost like 1860 1861 1866 1869 1872 | like 1859 |
a whale, insects in the water. ↑1 blocks not present in 1860 1861 1866 1869 1872; present in 1859 | Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.
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