| → yet some fundamental difference between them can always, or almost always, be detected. 1866 1869 |
| manner two parts in two organic beings, which owe but little of their structure in common to inheritance from the same ancestor. 1859 |
| manner two parts in two organic beings, which beings owe but little of their structure in common to inheritance from the same ancestor. 1860 1861 |
| yet fundamental differences between them can always be detected. 1872 |
|
| ↑ 10 blocks not present in 1859 1860 1861 1866 1869; present in 1872 |
| For instance, the eyes of cephalopods or cuttle-fish and of vertebrate animals appear wonderfully alike; and in such widely sundered groups no part of this resemblance can be due to inheritance from a common progenitor.
Mr. Mivart has advanced this case as one of special difficulty, but I am unable to see the force of his argument.
An organ for vision must be formed of transparent tissue, and must include some sort of lens for throwing an image at the back of a darkened chamber.
Beyond this superficial resemblance, there is hardly any real similarity between the eyes of cuttle-fish and vertebrates, as may be seen by consulting Hensen's admirable memoir on these organs in the Cephalopoda.
It is impossible for me here to enter on details, but I may specify a few of the points of difference.
The crystalline lens in the higher cuttle-fish consists of two parts, placed one behind the other like two lenses, both having a very different structure and disposition to what occurs in the vertebrata.
The retina is wholly different, with an actual inversion of the elemental parts, and with a large nervous ganglion included within the membranes of the eye.
The relations of the muscles are as different as it is possible to conceive, and so in other points.
Hence it is not a little difficult to decide how far even the same terms ought to be employed in describing the eyes of the Cephalopoda and Vertebrata.
It is, of course, open to any one to deny that the eye in either case could have been developed through the natural selection of successive, slight variations; but if this be admitted in the one case, it is clearly possible in the other; and fundamental differences of structure in the visual organs of two groups might have been anticipated, in accordance with this view of their manner of formation.
|
|
| → I am inclined to believe that, in 1866 1869 |
| As two men have sometimes independently hit on 1872 |
|
| → manner as two men have sometimes independently hit on the same 1866 1869 |
| OMIT 1872 |
|
| → natural 1866 1869 |
| in the several foregoing cases it appears that natural 1872 |
|
| → sometimes modified in nearly the same way two organs in two 1866 1869 |
| produced similar organs, as far as function is concerned, in distinct 1872 |
|
| → a remarkable work recently published, has investigated a nearly parallel case, in 1869 |
| a remarkable work recently published, has discussed a case nearly parallel with that of electric fishes, luminous insects, &c.; he undertook the laborious examination of this case in 1866 |
| OMIT 1872 |
|
| → views advanced 1869 |
| views advanced by me 1866 |
| conclusions arrived at 1872 |
|
| → volume. 1866 1869 |
| volume, has followed out with much care a nearly similar line of argument. 1872 |
|
| → species which possess an air-breathing apparatus, and are 1869 |
| members which are 1866 |
| species, possessing an air-breathing apparatus and 1872 |
|
| → OMIT 1869 1872 |
| the structure of 1866 |
|
| → circulating system, 1869 1872 |
| in their heart and system of circulation, 1866 |
|
| → with which their complex stomachs are lined, 1869 |
| with which their stomachs, equally complicated in both cases, are lined, 1866 |
| within their complex stomachs, 1872 |
|
| → whole structure of the water-breathing 1869 1872 |
| water-breathing 1866 |
|
| → that the equally important air-breathing apparatus would have been the same 1869 |
| from mere analogy that the equally important air-breathing apparatus would have been the same 1866 |
| that 1872 |
|
| → live on the land; and this might 1869 |
| are thus furnished; and this might 1866 |
| live on the land, the equally-important air-breathing apparatus would 1872 |
|
| → more confidently expected by those who believe in distinct creations; 1869 |
| more confidently expected by those who believe in the creation of each separate species; 1866 |
| same; 1872 |
|
| → to these species, have been made to differ, whilst all the 1869 |
| to a few species which are so closely similar or rather identical in all 1866 |
| have been made to differ, whilst all the other important organs were closely similar or rather identical. 1872 |
|
| → organs are closely similar or rather identical. 1869 |
| OMIT 1872 |
| points, have been made to differ? 1866 |
|
