| → these circumstances we know to be 1859 1860 1861 1866 1869 |
| all these circumstances are 1872 |
|
| →
a
2
,
1859 1861 1866 1869 1872 |
|
a
2
,
1860 |
|
| →
a
1
.
1859 1861 1866 1869 1872 |
|
a
1
.
1860 |
|
| →
8
2
,
1866 |
|
s
2
,
1859 1861 1869 1872 |
|
s
2
,
1860 |
|
| → irregular, nor that it goes on continuously; it is far more probable that each form remains for long periods unaltered, and then again undergoes modification. 1866 1869 1872 |
| irregular. 1859 1860 1861 |
|
| ↑ 1 blocks not present in 1859 1860 1861 1866; present in 1869 1872 |
| Nor do I suppose that the most divergent varieties are invariably preserved:
a medium form may often long endure, and may or may not produce more than one modified descendant; for natural selection will always act according to the nature of the places which are either unoccupied or not perfectly occupied by other beings; and this will depend on infinitely complex relations.
|
|
| → Nor do I suppose 1866 |
| I am far from thinking 1859 1860 1861 |
|
| → preserved: 1866 |
| prevail and multiply: 1859 1860 1861 |
|
|
which made the genus to which the parent-species belonged, a large genus in its own country. And
→these circumstances we know to be
to the production of new varieties. |
|
| If, then, these two varieties be variable, the most divergent of their variations will generally be preserved during the next thousand generations. And after this interval, variety
a
1
is supposed in the diagram to have produced variety
→
a
2
,
which will, owing to the principle of divergence, differ more from (A) than did variety
→
a
1
.
Variety
m
1
is supposed to have produced two varieties, namely
m
2
and
→
8
2
,
differing from each other, and more considerably from their common parent (A). We may continue the process by similar steps for any length of time; some of the varieties, after each thousand generations, producing only a single variety, but in a more and more modified condition, some producing two or three varieties, and some failing to produce any. Thus the varieties or modified
the common parent (A), will generally go on increasing in number and diverging in character. In the diagram the process is represented up to the ten-thousandth generation, and under a condensed and simplified form up to the fourteen-thousandth generation. |
|
| But I must here remark that I do not suppose that the process ever goes on so regularly as is represented
the diagram, though in itself made somewhat
→irregular, nor that it goes on continuously; it is far more probable that each form remains for long periods unaltered, and then again undergoes modification.
↑ →Nor do I suppose
that the most divergent varieties
invariably
→preserved:
a medium form may often long endure, and may or may not produce more than one modified descendant; for natural selection will always act according to the nature of the
|
