Origin of Species Variorum

Comparison with 1859

Text in this page (from paragraph 3200, sentence 130, word 17 to paragraph 3200, sentence 300, word 46) is not present in 1859

With these facts, here far too briefly and imperfectly given, which show that there is much graduated diversity in the eyes of living crustaceans, and bearing in mind how small the number of living animals is in proportion to those which have become extinct, I can see no very great difficulty (not more than in the case of many other structures) in believing that natural selection has converted the simple apparatus of an optic nerve merely coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the great Articulate class.

He who will go thus far, if he find on finishing this treatise that large bodies of facts, otherwise inexplicable, can be explained by the theory of descent, ought not to hesitate to go further, and to admit that a structure even as perfect as the eye of an eagle might be formed by natural selection, although in this case he does not know any of the transitional grades. ↑ His reason ought to conquer his imagination; though I have felt the difficulty far too keenly to be surprised at any degree of hesitation in extending the principle of natural selection to such startling lengths.

It is scarcely possible to avoid comparing the eye to

cluding divergent pencils of light, usually adhere to the cornea, but not rarely they are separate from it, and have their free ends convex; and in this case they must act as converging lenses. Altogether so diversified is the structure of the compound eyes, that Müller makes three main classes, with no less than seven sub-divisions of structure; he makes a fourth main class, namely, "aggregates" of stemmata, and he adds that "this is the transition-form between the mosaic-like compound eyes unprovided with a concentrating apparatus, and organs of vision with such an apparatus." ↑ With these facts, here .. too briefly and imperfectly given, which show how much graduated diversity there is in the eyes of our existing crustaceans, and bearing in mind how small the number of living animals is in proportion to those which have become extinct, I can see no very great difficulty (not more than in the case of many other structures) in believing that natural selection has converted the simple apparatus of an optic nerve merely coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the great Articulate class.

It is scarcely possible to avoid comparing the eye to