Origin of Species Variorum

→ instances, 1869 1872

and similar cases, 1866

→ graduated 1869 1872

cause of such a wide 1866

↑ 1 blocks not present in 1859 1860 1861 1869 1872; present in 1866

It was shown, when we discussed the air-breathing apparatus of certain crustaceans, that the process of adaptation for any purpose may start from two or more forms already differing from each other to a considerable degree, and that in almost all cases the nature of the variability, on which natural selection has to work, will be different; consequently, the final structure gained through natural selection, though serving for the same purpose, will be different.

→ many changes; 1872

a long course of modification; 1866 1869

→ again further altered. 1872

again. 1866 1869

→ it may serve, is 1872

used, will be 1866

used, is 1869

→ Finally then, although 1866 1869 1872

Although 1859 1860 1861

→ is to the extinct and unknown, 1869 1872

to the extinct and unknown 1859 1860 1861

OMIT 1866

→ OMIT 1869 1872

is very small, 1859 1860 1861

is very small 1866

→ I 1859 1860 1861 1869 1872

compared with the extinct and unknown forms, I 1866

→ It certainly is true, that new organs appearing as if created for some special purpose, rarely or never appear in any being;— as indeed is 1872

The truth of this remark is indeed 1859 1860

It certainly is not true, that new organs often appear suddenly in any class, as if created for some special purpose; as indeed is 1861

It certainly is true, that new organs very rarely or never suddenly appear in any class, as if created for some special purpose; as indeed is 1866

It certainly is true, that new organs appearing as if specially created for some purpose, rarely or never appear suddenly in any class; as indeed is 1869

→ but somewhat exaggerated, canon 1861 1866 1869 1872

canon 1859

but somewhat exaggerated canon 1860

→ so much variety and so little real novelty? 1872

so? 1859 1860 1861

so much variety and so little novelty? 1866 1869

→ great and sudden leap, 1872

leap, 1859 1860 1861

sudden leap, 1866 1869

→ short and sure, though slow 1872

the shortest and slowest 1859 1860

short and slow 1861

short and sure though slow 1866 1869

→ Importance, as affected by Natural Selection . 1872

importance .— 1859 1860 1861

Importance, as affected by Natural Selection. 1866

Importance, as affected by Natural Selection. 1869

→ the fittest, 1869 1872

individuals with any favourable variation, 1859 1860 1861 1866

→ the less well-fitted individuals, 1872

those with any unfavourable deviation of structure,— I have sometimes felt much difficulty in understanding the origin of simple parts, of which the importance does not seem sufficient to cause the preservation of successively varying individuals. 1859 1860 1861

those with any unfavourable deviation of structure,—I have sometimes felt much difficulty in understanding the origin of simple parts, of which the importance does not seem sufficient to cause the preservation of successively varying individuals. 1866

the less well fitted individuals,—I have sometimes felt great difficulty in understanding the origin or formation of parts of little importance; almost as great, though of a very different kind, as in the case of the most perfect and complex organs. 1869

→ great difficulty in understanding the origin or formation of parts of little importance; almost as great, 1872

as much difficulty, 1859 1860 1861 1866

→ OMIT 1872

on this head, 1859 1860 1861 1866

→instances, can we understand the →graduated scale of complexity and

of such

the

multifarious means for gaining the same

end,

both

the

case

forms

widely

remote

from

each

other

affinity,

and

with

forms

closely

allied

are

the

two

orchids

last

described?

The answer no doubt is, as already remarked, that when two forms vary, which already differ from each other

even

....

some

slight degree, the variability will not be of the same exact nature, and consequently the results obtained through natural selection for the same general purpose will not be the same. ↑ We

must

should

also bear in mind that every

well-developed

highly developed

organism has

already

....

passed through →many changes; and that each modified structure tends to be inherited, so that

each modification

will not readily be

lost,

wholly lost,

quite lost,

but may be

modified

....

again and →again further altered. Hence the structure of each part of each species, for whatever purpose →it may serve, is the sum of

the

....

many inherited changes, through which

that

the

species has passed during its successive adaptations to changed habits and conditions of life.

→Finally then, although in many cases it is most difficult

even to

conjecture by what transitions

many

....

organ

organs

could

....

have arrived at

its

their

present state; yet, considering

that

how small

the proportion of living and known forms →is to the extinct and unknown, →OMIT →I have been astonished how rarely an organ can be named, towards which no transitional grade is known to lead. →It certainly is true, that new organs appearing as if created for some special purpose, rarely or never appear in any being;— as indeed is shown by that

old

old,

→but somewhat exaggerated, canon in natural history of "Natura non facit saltum." We meet with this admission in the writings of almost every experienced naturalist;

or,

as Milne Edwards has well expressed it,

nature

Nature

is prodigal in variety, but niggard in innovation. Why, on the theory of Creation, should

this

there

be →so much variety and so little real novelty? Why should all the parts and organs of many independent beings, each supposed to have been separately created for its proper place in nature, be so

invariably

commonly

linked together by graduated steps? Why should not Nature

have

....

taken

take

leap

sudden leap

from structure to structure? On the theory of natural selection, we can clearly understand why she should not; for natural selection

can

....

act

acts

only by taking advantage of slight successive variations; she can never take a →great and sudden leap, but must advance by →short and sure, though slow steps.

Organs

little

apparent

→ Importance, as affected by Natural Selection .

As natural selection acts by life and

death,—by

death,—

the

preservation

survival

of →the fittest, and by the destruction of →the less well-fitted individuals,

— I

have sometimes felt →great difficulty in understanding the origin or formation of parts of little importance; almost as great, though of a very different kind, →OMIT as in the case