| → acts, as we have seen, exclusively 1861 1866 |
| exclusively acts 1869 |
| acts exclusively 1872 |
|
| → is 1861 1869 1872 |
| has been ex- posed 1866 |
|
| → at each successive period exposed. 1861 |
| at each successive period of time. 1866 |
| exposed at each successive period of life. 1869 |
| exposed at all periods of life. 1872 |
|
| → will, I think, 1861 |
| OMIT 1866 1869 1872 |
|
| → adult state, 1861 |
| same organic being (and, 1866 |
| same organic being, in the adult state 1869 1872 |
|
| → and 1861 1869 1872 |
| in the adult state), and 1866 |
|
| → Still 1861 1866 1869 |
| We see still 1872 |
|
|
|
| Natural
→acts, as we have seen, exclusively
by the preservation and accumulation of variations, which
beneficial under the organic and inorganic conditions
to which each creature
→is
→at each successive period exposed. The ultimate result
that each creature
to become more and more improved in relation to
This improvement
→will, I think,
inevitably
to the gradual advancement of the organisation of the greater number of living beings throughout the world. But here we enter on a very intricate subject, for naturalists have not defined to each
satisfaction what is meant by an advance in organisation. Amongst the vertebrata the degree of intellect and an approach in structure to man clearly come into play. It might be thought that the amount of change which the various parts and organs
in their development from the embryo to maturity would suffice as a standard of comparison; but there are cases, as with certain parasitic crustaceans, in which several parts of the structure become less perfect, so that the mature animal cannot be called higher than its larva. Von
standard seems the most widely applicable and the best, namely, the amount of differentiation of the
parts
the
→adult state,
as I should be inclined to
→and
their specialisation for different functions; or, as Milne Edwards would express it, the completeness of the division of physiological labour. But we shall see how obscure
subject
is if we look, for instance, to
amongst which some naturalists rank those as highest which, like the sharks, approach nearest to
whilst other naturalists rank the common bony or teleostean fishes as the highest, inasmuch as they are most strictly fish-like, and differ most from the other vertebrate classes.
→Still
more
|
