| → I do not doubt that 1859 1860 1861 1866 1869 |
| no doubt 1872 |
|
| → increased in the successive generations. 1859 1860 1861 1866 1869 |
| augmented. 1872 |
|
| →
a
10
.
1859 1861 1866 1869 1872 |
|
a
10
.
1860 |
|
|
places which are either unoccupied or not perfectly occupied by other beings; and this will depend on infinitely complex relations. But as a general rule, the more diversified in structure the descendants from any one species can be rendered, the more places they will be enabled to seize on, and the more their modified progeny will
In our diagram the line of succession is broken at regular intervals by small numbered letters marking the successive forms which have become sufficiently distinct to be recorded as varieties. But these breaks are imaginary, and might have been inserted
after intervals long enough to
the accumulation of a considerable amount of divergent variation. |
|
| As all the modified descendants from a common and widely-diffused species, belonging to a large genus, will tend to partake of the same advantages which made their parent successful in life, they will generally go on multiplying in number as well as diverging in character: this is represented in the diagram by the several divergent branches proceeding from (A). The modified offspring from the later and more highly improved branches in the lines of descent, will, it is probable, often take the place of, and so destroy, the earlier and less improved branches: this is represented in the diagram by some of the lower branches not reaching to the upper horizontal lines. In some cases
→I do not doubt that
the process of modification will be confined to a single line of descent, and the number of
descendants will not be increased; although the amount of divergent modification may have been
→increased in the successive generations. This case would be represented in the diagram, if all the lines proceeding from (A) were removed, excepting that from
a
1
to
→
a
10
.
In the same
the English race-horse
|
