| → plant. 1859 1860 1861 |
| plants in each great class on a uniformly regulated plan: but this is not a scientific explanation. 1866 |
| plants in each great class on a uniform plan; but this is not a scientific explanation. 1869 1872 |
|
| → manifest 1859 1860 1861 1866 1869 |
| to a large extent simple 1872 |
|
| → and become gradually 1859 1860 1861 1866 |
| becoming at the same time 1869 1872 |
|
| → to any extent, 1859 1860 1861 1866 |
| OMIT 1869 1872 |
|
| → this great amount of modification there will be no tendency 1859 1860 1861 |
| this great amount of modification there would be no tendency 1866 |
| this modification would not tend 1869 |
| these modifications would not tend 1872 |
|
| → the ancient progenitor, 1859 1860 1861 1866 |
| an early progenitor,— 1869 |
| an early progenitor— 1872 |
|
| → had 1859 1860 1861 1866 1869 |
| birds, and reptiles, had 1872 |
|
|
purposes, are formed by infinitely numerous modifications of an upper lip, mandibles, and two pairs of maxillæ.
the construction of the mouths and limbs of crustaceans. So it is with the flowers of plants. |
|
| Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility or by the doctrine of final causes. The hopelessness of the attempt has been expressly admitted by Owen in his most interesting work on the 'Nature of Limbs.' On the ordinary view of the
creation of each being, we can only say that so it is;— that it has
pleased the Creator to construct
and
→plant.
|
|
| The explanation is
→manifest
the theory of the
selection of successive slight modifications,— each modification being profitable in some way to the modified form, but often affecting by correlation
other parts of the organisation. In changes of this nature, there will be little or no tendency to
the original pattern, or to transpose
The bones of a limb might be shortened and
to any extent,
→and become gradually
enveloped in thick membrane, so as to serve as a fin; or a webbed
might have all its bones, or certain
lengthened to any extent,
the membrane connecting them
→to any extent,
so as to serve as a
yet
all
→this great amount of modification there will be no tendency
to alter the framework of
or the relative connexion of the
parts. If we suppose that
→the ancient progenitor,
the archetype as it may be
of all mammals,
→had
its limbs constructed on the existing general pattern, for whatever purpose they served, we can at once perceive the plain signification of the homologous construction of the limbs throughout the
class. So with the mouths of insects, we have only to
|
