Origin of Species Variorum

→ and afterwards spread, so that 1872

so that whatever intercrossing took place would be chiefly between 1859 1860 1861 1866

and afterwards spread, so that the crossing would be chiefly between 1869

→ new variety would chiefly cross together. 1872

same new variety. 1859 1860 1861 1866

new variety living together in the same place. 1869

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

A local variety when once thus formed might subsequently slowly spread to other districts.

→ OMIT 1869 1872

same variety, as the 1859 1860 1861 1866

→ OMIT 1869 1872

with other varieties 1859 1860 1861 1866

→ with 1872

in the case of slow-breeding 1859 1860 1861 1866

in the case of 1869

→ unite 1859 1860 1861 1866 1872

breed slowly and unite 1869

→ and which do not propagate rapidly, we 1872

we 1859 1860 1861 1866 1869

→ assume that free intercrossing would always eliminate 1872

overrate 1859 1860 1861 1866

assume that 1869

→ OMIT 1869 1872

intercrosses in retarding 1859 1860 1861 1866

→ for 1859 1860 1861 1866 1872

will always be immediately overpowered by free intercrossing; for 1869

→ forward a considerable body 1872

a considerable catalogue 1859 1860 1861 1866

a considerable body 1869

→ the individuals of each variety 1872

varieties of the same kind 1859 1860 1861 1866 1869

→ as already stated, 1872

I have already attempted to show that 1859 1860 1861 1866

as already stated 1869

→ of time, 1869 1872

I am convinced that 1859 1860

OMIT 1861 1866

→ With respect to 1872

If there exist 1859 1860 1861 1866 1869

→ extremely low in the scale, which do not propagate sexually, nor conjugate, and which cannot possibly 1872

which never 1859 1860 1861 1866 1869

→ under the same 1872

as long as their 1859 1860 1861 1866 1869

→ OMIT 1872

remain the same, 1859 1860 1861 1866 1869

→ which will destroy any individuals departing 1872

destroying any which depart 1859 1860 1861 1866 1869

→ If the 1872

but if their 1859 1860 1861 1866 1869

→ modification of 1872

process of 1859 1860 1861 1866

changes effected through 1869

→ species through natural 1872

natural 1859 1860 1861 1866 1869

→ almost 1869 1872

in a great degree 1859 1860 1861 1866

→ varying individuals of the same species 1869 1872

individuals of a varying species throughout the area 1859 1860 1861 1866

→ surrounding 1869 1872

same species, which otherwise would have inhabited the surrounding and differently circumstanced 1859 1860 1861

same species, which othewise would have inhabited the surrounding and differently circumstanced 1866

→ also, be thus 1872

be 1859 1860 1861 1866

also, be 1869

birth, but which wander little and

which

....

can increase at a

very

....

rapid rate, a new and improved variety might be quickly formed on any one spot, and might there maintain itself in a

body,

body

→and afterwards spread, so that the individuals of the →new variety would chiefly cross together. ↑ On

the above

this

principle, nurserymen always prefer

getting

saving

seed from a large body of

plants

plants,

the →OMIT chance of intercrossing →OMIT is thus lessened.

Even →with

animals,

animals

which →unite for each birth, →and which do not propagate rapidly, we must not →assume that free intercrossing would always eliminate the effects of →OMIT natural

selection

selection;

→for I can bring →forward a considerable body of

facts,

facts

showing that within the same area,

varieties

two varieties

of the same animal

can

may

long remain distinct, from haunting different stations, from breeding at slightly different seasons, or from →the individuals of each variety preferring to pair together.

Intercrossing plays a very important part in nature

keeping the individuals of the same species, or of the same variety, true and uniform in character. It will obviously thus act far more efficiently with those animals which unite for each birth;

but

but,

→as already stated, we have reason to believe that occasional intercrosses take place with all animals and

with all

....

plants. Even if these take place only at long

intervals,

intervals

→of time, the young thus produced will gain so much in vigour and fertility over the offspring from long-continued self-fertilisation, that they will have a better chance of surviving and propagating their kind; and thus, in the long run, the influence of

intercrosses,

crosses,

even at rare intervals, will be great. →With respect to organic beings →extremely low in the scale, which do not propagate sexually, nor conjugate, and which cannot possibly intercross, uniformity of character can be retained

amongst

them,

them

→under the same conditions of

life

life,

→OMIT only through the principle of

inheritance

inheritance,

and through natural selection →which will destroy any individuals departing from the proper

type;

type.

→If the conditions of life change and

they

the

undergo

form undergoes

modification, uniformity of character can be given to

their

the

modified offspring, solely by natural selection preserving

the same

similar

favourable variations.

Isolation, also, is an important element in the →modification of →species through natural selection. In a confined or isolated area, if not very large, the organic and inorganic conditions of life will generally be →almost uniform; so that natural selection will tend to modify all the →varying individuals of the same species in the same

manner

relation

the

same

conditions.

Intercrosses,

also,

with the

individuals

inhabitants

of the →surrounding

districts,

districts

will

will,

→also, be thus prevented. Moritz Wagner has lately published an interesting essay on this subject, and has shown that the service rendered by isolation in preventing crosses between

newly

newly-