Origin of Species Variorum

→ physical conditions at least 1860

conditions 1859

physical conditions 1861 1866

→ most affect those animals 1859 1860 1861 1866

affect those animals most 1869

chiefly affect those animals 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

and afterwards spread, so that 1872

→ same new variety. 1859 1860 1861 1866

new variety living together in the same place. 1869

new variety would chiefly cross together. 1872

→ same variety, as the 1859 1860 1861 1866

OMIT 1869 1872

→ with other varieties 1859 1860 1861 1866

OMIT 1869 1872

→ in the case of slow-breeding 1859 1860 1861 1866

in the case of 1869

with 1872

→ unite 1859 1860 1861 1866 1872

breed slowly and unite 1869

→ we 1859 1860 1861 1866 1869

and which do not propagate rapidly, we 1872

→ overrate 1859 1860 1861 1866

assume that 1869

assume that free intercrossing would always eliminate 1872

→ intercrosses in retarding 1859 1860 1861 1866

OMIT 1869 1872

→ for 1859 1860 1861 1866 1872

will always be immediately overpowered by free intercrossing; for 1869

→ a considerable catalogue 1859 1860 1861 1866

a considerable body 1869

forward a considerable body 1872

→ varieties of the same kind 1859 1860 1861 1866 1869

the individuals of each variety 1872

this case the effects of intercrossing can hardly be

coun-

....

terbalanced

counterbalanced

by natural selection always tending to modify all the individuals in each district in exactly the same manner to the conditions of each; for in a continuous area, the →physical conditions at least will generally graduate away insensibly from one district to another.

~~The~~

The

Intercrossing

intercrossing

will →most affect those animals which unite for each

birth

birth,

and

which

wander much, and which do not breed at a very quick rate. Hence

with

animals of this nature, for

instance,

instance

birds, varieties will generally be confined to separated countries; and this I

find

believe

to be the case.

With

hermaphrodite organisms which cross only occasionally, and likewise

with

animals which unite for each birth, but which wander little and

~~which~~

which

can increase at a

~~very~~

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,

→so that whatever intercrossing took place would be chiefly between the individuals of the →same new variety. A local variety when once thus formed might subsequently slowly spread to other districts. On

this

the above

principle, nurserymen always prefer

saving

getting

seed from a large body of

plants,

plants

the →same variety, as the chance of intercrossing →with other varieties is thus lessened.

Even →in the case of slow-breeding

animals

animals,

which →unite for each birth, →we must not →overrate the effects of →intercrosses in retarding natural

selection

selection;

→for I can bring →a considerable catalogue of

facts

facts,

showing that within the same area,

two varieties

varieties

of the same animal

may

can

long remain distinct, from haunting different stations, from breeding at slightly different seasons, or from →varieties of the same kind 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