| → a new area, they 1859 1860 1861 |
| a new area, these 1866 |
| an area, many of the older species 1869 1872 |
|
| → many of the old inhabitants; 1859 1860 1861 |
| many of the older species; 1866 |
| OMIT 1869 1872 |
|
| → parts of the world, 1859 1860 1861 1866 1869 |
| regions, 1872 |
|
|
between our consecutive formations; and in these intervals there may have been much slow extermination. Moreover,
by sudden immigration or by unusually rapid development, many species of a new group have taken possession of
→a new area, they
will have
in a correspondingly rapid
→many of the old inhabitants;
and the forms which thus yield their places will commonly be allied, for they will partake of
inferiority in common. |
|
| Thus, as it seems to me, the manner in which single species and whole groups of species become
accords well with the theory of natural selection. We need not marvel at extinction; if we must marvel, let it be at our
in imagining for a moment that we understand the many complex
on which the existence of each species depends. If we forget for an instant, that each species tends to increase inordinately, and that some check is always in action, yet seldom perceived by us, the whole economy of nature will be utterly obscured. Whenever we can precisely say why this species is more abundant in individuals than that; why this species and not another can be naturalised in a given country; then, and not
then, we may justly feel surprise why we cannot account for the extinction of
particular species or
of species. |
|
|
| Scarcely any palæontological discovery is more striking than the fact, that the forms of life change almost simultaneously throughout the world. Thus our European Chalk formation can be recognised in many distant
→parts of the world,
under the most different climates, where not a fragment of the mineral chalk itself can be found;
in North
|
