| → under new conditions of life may 1872 |
| may under new conditions of life 1859 1860 1861 1866 1869 |
|
| → it may have 1872 |
| have 1859 1860 1861 1866 1869 |
|
| → OMIT 1872 |
| and their intermediate states 1859 1860 1861 1866 1869 |
|
| → in part or in whole specialised 1866 1869 1872 |
| specialised 1859 1860 1861 |
|
| → in external appearance 1872 |
| appearing 1866 1869 |
|
| → In many cases we 1872 |
| We 1859 1860 1861 |
| In almost every case we 1866 1869 |
|
| → OMIT 1866 1869 1872 |
| in almost every case, 1859 1860 1861 |
|
| → In many other cases, modifi- cations are probably the direct result of 1872 |
| But we may confidently believe that many modifications, wholly due to 1859 1860 1861 1866 1869 |
|
|
We have seen in this chapter how cautious we should be in concluding that the most different habits of life could not graduate into each other; that a bat, for instance, could not have been formed by natural selection from an animal which at first
only
through the air. |
|
| We have seen that a species
→under new conditions of life may
change its
or
→it may have
diversified habits, with some
very unlike those of its nearest congeners. Hence we can understand, bearing in mind that each organic being is trying to live wherever it can live, how it has arisen that there are upland geese with webbed feet, ground woodpeckers, diving thrushes, and petrels with the habits of auks. |
|
| Although the belief that an organ so perfect as the eye could have been formed by natural selection, is
enough to stagger any one; yet in the case of any organ, if we know of a long series of
in complexity, each good for its possessor, then, under changing conditions of
there is no logical impossibility in the acquirement of any conceivable degree of perfection through natural selection. In the cases in which we know of no intermediate or transitional states, we should be
cautious in concluding that none
have existed, for the
of many organs
→OMIT
show
wonderful
in function are at least possible. For instance, a
has apparently been converted into an air-breathing lung. The same organ having performed simultaneously very different functions, and then having been
→in part or in whole specialised
for one function; and two
distinct organs having performed at the same time the same function, the one having been perfected whilst aided by the other, must often have largely facilitated transitions. |
|
| We have seen
two beings widely remote from each other in the natural scale,
serving
for the same purpose and
→in external appearance
closely similar may have been separately and independently formed; but when such organs are closely examined, essential differences in their structure can almost always be detected; and this naturally follows from the principle of natural selection. On the other hand, the common rule throughout nature is infinite diversity of structure for gaining the same end; and this again naturally follows
the same great principle. |
|
|
→In many cases we
are far too
→OMIT
to be enabled to assert that
part or organ is so unimportant for the welfare of a species, that modifications in its structure could not have been slowly accumulated by means of natural selection.
→In many other cases, modifi- cations are probably the direct result of
|
