See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1866
1869
1872

Altogether so diversified is the structure of the compound eyes, 1861
But these organs in the Articulata are so much diversified 1872

no less than 1861
OMIT 1872

of structure; he makes 1861
besides 1872

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." 1861
of aggregated simple eyes. 1872

2 blocks not present in 1861 1866 1869 1872; present in 1859 1860
In certain crustaceans, for instance, there is a double cornea, the inner one divided into facets, within each of which there is a lens-shaped swelling. In other crustaceans the transparent cones which are coated by pigment, and which properly act only by excluding lateral pencils of light, are convex at their upper ends and must act by convergence; and at their lower ends there seems to be an imperfect vitreous substance.

With 1859 1860 1861
When we reflect on 1866 1869 1872

and imperfectly given, which show how much graduated diversity 1861
and imperfectly given, which show that there is much graduated diversity 1859 1860
and imperfectly, with respect to the wide, diversified, and graduated range of structure 1866
with respect to the wide, diversified, and graduated range of structure 1869 1872

there is in 1861
in 1859 1860 1866 1869 1872

our existing crustaceans, and bearing 1861
living crustaceans, and bearing 1859 1860
the existing Articulata; and when we bear 1866
the lower animals; and when we bear 1869 1872

living animals is in proportion to 1859 1860 1861
all living forms must be in comparison with 1866 1872
all the forms now living must be in comparison with 1869

I can see no 1859 1860 1861
the difficulty ceases to be 1866 1869 1872

difficulty (not more than in the case of many other structures) 1859 1860 1861
(not more so than in the case of many other structures) 1866
OMIT 1869 1872

if 1859 1860 1861 1866
ought not to hesitate to go one step further, if 1869 1872

descent, ought not to hesitate to go further, and 1859 1860 1861
descent with modification, ought not to hesitate to go further, and 1866
descent with modification; he ought 1869
modification through natural selection; he ought 1872

the eye of 1859 1860 1861 1866
OMIT 1869 1872

might 1859 1860 1861 1866
eye might 1869
eye might thus 1872

by natural selection, 1859 1860 1861 1866 1869
OMIT 1872

1 blocks not present in 1859 1860 1861 1866; present in 1869 1872
It has been objected that in order to modify the eye and still preserve it as a perfect instrument, many changes would have to be effected simultaneously, which, it is assumed, could not be done through natural selection; but as I have attempted to show in my work on the variation of domestic animals, it is not necessary to suppose that all the modifications were simultaneous, if they were extremely slight and gradual.

His reason ought to conquer his imagination; though 1859 1860 1861
To arrive, however, at a just conclusion regarding the formation of the eye, with all its marvellous yet not absolutely perfect characters, it is indispensable that the reason should conquer the imagination; but 1872

any degree of hesitation in extending 1859 1860 1861
others hesitating to extend 1872

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
Müller
formerly made
makes
three main
classes
classes,
with no less than seven
subdivisions,
sub-divisions
of structure; he makes a fourth main
class
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
far
given
given much
....
too
briefly,
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
may have
has
converted the simple apparatus of an optic
nerve,
nerve
merely
merely
coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the
great
great
Articulate
Class.
class.
He who will go thus far, if he
should find
finds
find
on finishing this
volume
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
eagles
eagle's
eagle
might
have been
be
formed,
formed
by natural selection, although in this case he does not know
any of
any of
the transitional
steps.
states.
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
so
such
startling
a length.
lengths.
It is scarcely possible to avoid comparing the eye
with
to