| → it must by my 1859 1860 1861 |
| whether known or not yet known, it must by my 1866 1869 |
| whether known or unknown, it must on this 1872 |
|
| → use and disuse, being slightly 1859 1860 1861 1866 |
| use and disuse, being 1869 |
| the increased use or disuse of parts, being 1872 |
|
| → growth. 1859 1860 1861 1866 1869 |
| growth and variation. 1872 |
|
| → adaptations, 1859 1860 1861 1866 1869 |
| variations and adaptations, 1872 |
|
|
the larger country there will have existed more
and more diversified forms, and the
will have been severer, and thus the standard of perfection will have been rendered higher. Natural selection will not necessarily
absolute perfection; nor, as far as we can judge by our limited faculties, can absolute perfection be everywhere
|
|
| On the theory of natural selection we can clearly understand the full meaning of that old canon in natural history, "Natura non facit saltum." This canon, if we look
to the present inhabitants
the world, is not strictly
but if we include all those of past times,
→it must by my
theory be strictly true. |
|
| It is generally acknowledged that all organic beings have been formed on two great
of Type, and the Conditions of Existence. By unity of type is meant that fundamental agreement in
which we see in organic beings of the same class, and which is quite independent of their habits of life. On my theory, unity of type is explained by unity of descent. The expression of conditions of existence, so often insisted on by the illustrious Cuvier, is fully embraced by the principle of natural selection. For natural selection acts by either now adapting the varying parts of each being to its organic and inorganic conditions of life; or by having adapted them during
periods of time: the adaptations being aided in
cases by
→use and disuse, being slightly
affected by the direct action of the external conditions of life, and
in all cases
to the several laws of
→growth. Hence, in fact, the law of the Conditions of Existence is the higher law; as it includes, through the inheritance of former
→adaptations,
that of Unity of Type.
|
