Origin of Species Variorum

↑ 2 blocks not present in 1859 1860; present in 1861 1866 1869 1872

It may perhaps be doubted whether monstrosities, or such sudden and great deviations of structure as we occasionally see in our domestic productions, more especially with plants, are ever permanently propagated in a state of nature. Monsters are very apt to be sterile; and almost every part of every organic being, at least with animals, is so beautifully related to its complex conditions of life that it seems as improbable that any part should have been suddenly produced perfect, as that a complex machine should have been invented by man in a perfect state.

↑ 3 blocks not present in 1859 1860 1861; present in 1866 1869 1872

Under domestication monstrosities sometimes occur which resemble normal structures in widely different animals. Thus pigs have occasionally been born with a sort of proboscis, and if any wild species of the same genus had naturally possessed a proboscis, it might have been argued that this had appeared as a monstrosity; but I have as yet failed to find, after diligent search, cases of monstrosities resembling normal structures in nearly allied forms, and these alone bear on the question. If monstrous forms of this kind ever do appear in a state of nature and are capable of reproduction (which is not always the case), as they occur rarely and singly, their preservation would depend on unusually favourable circumstances.

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

If perpetuated in this crossed state, their preservation will be almost necessarily due to the modification being in some way beneficial to the animal under its then existing conditions of life; so that, even in this case, natural selection will come into play.

←Subtitle not present 1859 1860 1861 Individual Differences. 1866

→ highly 1859 1860 1861 1866

of the highest 1869 1872

→ afford 1859 1860

are often inherited, as must be familiar to every one; and thus they afford 1861 1866

are often inherited, as must be familiar to every one; and they thus afford 1869 1872

→ accumulate, 1859 1860 1861

act on and accumulate, 1866 1869 1872

→ I should have expected 1859 1860

it might have been thought 1861 1866 1869 1872

plants on Alpine summits, or the thicker fur of an animal from far northwards, would not in some cases be inherited for at least

some

few generations? and in this case I presume that the form would be called a variety. ↑ ↑ ↑ →

Again, we have many slight differences which may be called individual differences, such as are known

fre- quently

frequently

to appear in the offspring from the same parents, or which may be presumed to have thus arisen, from being frequently observed in the individuals of the same species inhabiting the same confined locality. No one supposes that all the individuals of the same species are cast in the

~~very~~

very

same

actual mould.

mould.

These individual differences are →highly

importance

important

for us,

for

they →afford materials for natural selection to →accumulate, in the same manner as man

~~can~~

can

accumulates

accumulate

in any given direction individual differences in his domesticated productions. These individual differences generally affect what naturalists consider unimportant parts; but I could show by a long catalogue of facts, that parts which must be called important, whether viewed under a physiological or classificatory point of view, sometimes vary in the individuals of the same species. I am convinced that the most experienced naturalist would be surprised at the number of the cases of variability, even in important parts of structure, which he could collect on good authority, as I have collected, during a course of years.

should be remembered that systematists are far from

being pleased

pleased

at finding variability in important characters, and that there are not many men who will laboriously examine internal and important organs, and compare them in many specimens of the same species.

It would

I should

never have

been expected

expected

that the branching of the main nerves close to the great central ganglion of an insect would have been variable in the same species; →I should have expected that changes of this nature could have been effected only