| → successive variations would almost certainly be in some degree different, and the newly-formed variety would probably 1869 1872 |
| newly-formed fantail would be almost sure to 1859 1861 1866 |
| newly-formed faintail would be almost sure to 1860 |
|
| → when 1866 1869 1872 |
| does not reappear after 1859 1860 1861 |
|
| → never reappears; that is, 1866 1869 1872 |
| or 1859 1860 1861 |
|
| ↑ 1 blocks not present in 1869 1872; present in 1859 1860 1861 1866 |
| For as all the species of the same group have descended from some one species, it is clear that
as long as any species of the group have appeared in the long succession of ages,
so long must its
members have continuously
existed, in order to have
generated
either new
and modified
or the same
old and unmodified forms.
|
|
| → of each 1869 |
| one from the 1872 |
|
| → of some 1869 |
| all from a 1872 |
|
| → the species which have successively appeared at all ages must have been connected 1869 1872 |
| must have continuously existed 1859 1860 1861 1866 |
|
| → many species of a group 1866 1869 |
| the species of a group 1859 1860 1861 |
| whole groups of species 1872 |
|
| → come in abruptly 1861 1866 1869 |
| come in abruptly; 1859 1860 |
| been abruptly developed; 1872 |
|
| → in a body; and 1861 1866 1869 |
| and 1859 1860 1872 |
|
|
well-established
of the domestic pigeon, for the
→successive variations would almost certainly be in some degree different, and the newly-formed variety would probably
inherit from its
progenitor some
characteristic differences. |
|
| Groups of species, that is, genera and families, follow the same general rules in their appearance and disappearance as do single species, changing more or less quickly, and in a greater or lesser degree. A
→when
it has once
→never reappears; that is,
its existence, as long as it lasts, is continuous. I am aware that there are some apparent exceptions to this rule, but the exceptions are surprisingly few, so
that E. Forbes , Pictet, and Woodward (though all strongly opposed to such views as I maintain) admit its truth; and the rule strictly accords with
theory. ↑
For all the species of the same group, however long it may have lasted, are the modified
→of each
other, and
→of some
common progenitor.
the genus Lingula, for instance,
→the species which have successively appeared at all ages must have been connected
an unbroken
of generations, from the lowest Silurian stratum to the present day. |
|
| We have seen in the last chapter that
→many species of a group
sometimes falsely appear to have
→come in abruptly
→in a body; and
I have attempted to give an explanation of this fact, which if true would
fatal to my views. But such cases are certainly exceptional; the general rule being a gradual increase in number,
the group reaches its maximum, and then, sooner or later,
If the number of the species
a genus, or the number of the genera
a family, be represented by a vertical line of varying thickness,
the successive geological formations in which the species are found, the line will sometimes falsely appear to begin at its lower end, not in a sharp point, but abruptly; it then gradually
|
