Origin of Species Variorum

→ same breed of the pigeon, and 1872

pigeon; 1859 1860 1861 1866 1869

→ that of the 1869 1872

the 1859 1860 1861 1866

→ perfect birds, many departing 1872

to perfection, and frequently individuals are born which depart 1859 1860 1861 1866

perfect birds, some frequently departing 1869

→ new variations, 1872

further variability of all kinds, 1859 1860 1861 1866

further variability, 1869

→ OMIT 1869 1872

there may always be expected to be 1859 1860 1861 1866

→ modification may always be expected. 1869 1872

modification. 1859 1860 1861 1866

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

It further deserves notice that these variable characters, produced by man's selection, sometimes become attached, from causes quite unknown to us, more to one sex than to the other, generally to the male sex, as with the wattle of carriers and the enlarged crop of pouters.

→ has come not 1872

comes 1859 1860 1861 1866 1869

→ degree. 1861 1866 1869 1872

degree. For in this case the variability will seldom as yet have been fixed by the continued selection of the individuals varying in the required manner and degree, and by the continued rejection of those tending to revert to a former and less modified condition. 1859 1860

the

breeds

individuals

of the →same breed of the pigeon, and see what a prodigious amount of difference there is in the

beak

beaks

the different

....

tumblers, in the

beak

beaks

and wattle of

the different

....

carriers, in the carriage and tail of

our

....

fantails, &c., these being the points now mainly attended to by English fanciers. Even in

~~the~~

the

sub-breeds,

same sub-breed,

as in →that of the short-faced

tumblers,

tumbler,

it is notoriously difficult to breed

them

....

nearly →perfect birds, many departing widely from the standard. There may

be truly

truly be

said to be a constant struggle going on between, on the one hand, the tendency to reversion to a less

modified

perfect

state, as well as an innate tendency to →new variations, and, on the other hand, the power of steady selection to keep the breed true. In the long run selection gains the day, and we do not expect to fail so

far

completely

as to breed

....

bird as coarse as a common tumbler

from

pigeon from

a good short-faced strain. But as long as selection is rapidly going on, →OMIT much variability in the

structure

parts

undergoing →modification may always be expected. ↑

Now let us turn to nature. When a part has been developed in an extraordinary manner in any one species, compared with the other species of the same genus, we may conclude that this part has undergone an extraordinary amount of

modification,

modification

since the period when the

species

several species

branched off from the common progenitor of the genus. This period will seldom be remote in any extreme degree, as species

very

....

rarely endure for more than one geological period. An extraordinary amount of modification implies an unusually large and long-continued amount of variability, which has continually been accumulated by natural selection for the benefit of the species. But as the variability of the

extraordinarily-developed

extraordinarily developed

part or organ has been so great and long-continued within a period not

exces- sively

excessively

remote, we might, as a general rule,

expect still

still expect

to find more variability in such parts than in other parts of the

organisation,

organisation

which have remained for a much longer period nearly constant. And this, I am convinced, is the case. That the struggle between natural selection on the one hand, and the tendency to reversion and variability on the other hand, will in the course of time cease; and that the most abnormally developed organs may be made constant, I

can

....

see no reason to doubt.

Hence

Hence,

when an organ, however abnormal it may be, has been transmitted in approximately the same condition to many modified descendants, as in the case of the wing of the bat, it must have existed, according to

our

theory, for an immense period in nearly the same state; and thus it →has come not to be

....

more variable than any other structure. It is only in those cases in which the modification has been comparatively recent and extraordinarily great that we ought to find the generative

variability,

variability ,

as it may be called, still present in a high →degree. For