Origin of Species Variorum

→ the difficulty ceases to be 1866 1869 1872

I can see no 1859 1860 1861

→ (not more so than in the case of many other structures) 1866

difficulty (not more than in the case of many other structures) 1859 1860 1861

OMIT 1869 1872

→ if 1859 1860 1861 1866

ought not to hesitate to go one step further, if 1869 1872

→ descent with modification, ought not to hesitate to go further, and 1866

descent, ought not to hesitate to go further, and 1859 1860 1861

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.

→ Vertebrata, so manifestly the 1866

OMIT 1869

→ we 1866

namely the Vertebrata, we 1869

→ as in the former cases, 1866

OMIT 1869

→ such as exists 1866

so simple, that it consists, as 1869

→ fish called the lancelet, which is so simple that it consists only 1866

lancelet, 1869

→ skin, lined with pigment and 1866

transparent skin, 1869

→ but 1866

and lined with pigment, but 1869

→ the class both of 1866

both 1869

→ merely 1866

in the embryo 1869

→ cells of the epidermis, 1866

epidermic cells, 1869

→ that the naturalist who reflects on the origin and manner of 1866

in order to arrive at a just conclusion regarding the 1869

→ attributes, should make his reason conquer his imagina- tion; though 1866

characters, that the reason should conquer the imagination; but 1869

those which have become extinct, →the difficulty ceases to be very great →(not more so than in the case of many other structures) in believing that natural selection

has

may have

converted the simple apparatus of an optic

nerve

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~~

great

Articulate

class.

Class.

He who will go thus far, →if he

find

finds

should find

on finishing this

treatise

volume

that large bodies of facts, otherwise inexplicable, can be explained by the theory of →descent with modification, 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

formed,

formed

→by natural selection, although in this case he does not know

any of

....

the transitional

grades.

states.

steps.

↑ Even in the →Vertebrata, so manifestly the most highly

organised

organized

division of the animal kingdom, →we can

start

start,

→as in the former cases, from an

eye

eye,

→such as exists in the →fish called the lancelet, which is so simple that it consists only of a little

~~fold-like~~

fold-like

sack of →skin, lined with pigment and furnished with a

nerve

nerve,

→but destitute of any other

apparatus.

~~being~~

~~merely~~

~~covered~~

~~transparent~~

~~membrane.~~

In →the class both of fishes and reptiles, as Owen has remarked, "the range of gradations of dioptric structures is very great." It is a significant fact that even in man, according to the high authority of Virchow, the beautiful crystalline lens is

~~originally~~

originally

formed →merely by an accumulation of →cells of the epidermis, lying in a sack-like fold of the skin; and the vitreous body is formed from embryonic sub-cutaneous tissue. It is indeed

indispensable,

indispensable

→that the naturalist who reflects on the origin and manner of formation of the eye, with all its marvellously perfect →attributes, should make his reason conquer his imagina- tion; though