Origin of Species Variorum

→ law 1859 1860 1861 1866 1869

very general, if not universal, law 1872

→ for the production of new forms through Natural Selection. 1869

to Natural Selection .— 1859

to Natural Selection. — 1860 1861

to Natural Selection. 1866

for the production of new forms through Natural Selection. 1872

→ variability, under which term 1869 1872

inheritable and diversified variability is favourable, but I believe mere 1859 1860

variability will evidently be favourable for the work of natural selection, but mere 1861 1866

→ are always included, will evidently be favourable. 1869 1872

suffice for the work. 1859 1860

probably suffice. 1861 1866

→ for the appearance of profitable variations within any given period, 1869

for the appearance within any given period of profitable variations, 1859 1860 1861 1866

within any given period for the appearance of profitable variations, 1872

→ OMIT 1861 1866 1869 1872

it may be said, 1859 1860

→ selection. 1861 1866 1869

selection. The tendency to reversion may often check or prevent the work; but as this tendency has not prevented man from forming by selection numerous domestic races, why should it prevail against natural selection? 1872

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

Non-inheritance of any new character is, in fact, the same thing as reversion to the character of the grandparents or more remote ancestors; and no doubt the tendency to reversion may often have checked or prevented the action of natural selection; but its importance has been greatly exaggerated by some writers.

→ may often check or prevent the work; but as this tendency has 1869

has 1861 1866

→ forming by selection numerous domestic races, 1869

creating innumerable hereditary races in the animal and vegetable kingdoms, 1861 1866

→ prevail against 1869

have stopped the process of 1861 1866

→ the case of 1869 1872

man's 1859 1860 1861 1866

→ free intercrossing will wholly stop 1859 1860 1861 1866 1869

if the individuals be allowed freely to intercross, 1872

occasional intercross

between

with a

distinct

individuals

individual

is a →law of nature. I am well aware that there are, on this view, many cases of difficulty, some of which I am trying to investigate. Finally then, we may conclude that in many organic beings, a cross between two individuals is an obvious necessity for each birth; in many others it occurs perhaps only at long intervals; but in none, as I suspect, can self-fertilisation go on for perpetuity.

Circumstances

favourable

→ for the production of new forms through Natural Selection.

This is an extremely intricate subject. A

large

great

amount of →variability, under which term individual differences →are always included, will evidently be favourable. A large number of individuals, by giving a better chance →for the appearance of profitable variations within any given period, will compensate for a lesser amount of variability in each individual, and is, I believe,

a highly

an extremely

important element of success. Though

nature

Nature

grants

vast

long

periods of time for the work of natural selection, she does not grant an indefinite period; for as all organic beings are

striving,

striving

→OMIT to seize on each place in the economy of nature, if any one species does not become modified and improved in a corresponding degree with its competitors, it will

soon

....

be exterminated. Unless favourable variations be inherited by some at least of the offspring, nothing can be effected by natural →selection. ↑

If the

The

tendency to reversion →may often check or prevent the work; but as this tendency has not prevented man from →forming by selection numerous domestic races, why should it →prevail against natural selection?

In →the case of methodical selection, a breeder selects for some definite object, and →free intercrossing will wholly stop