→ for 1859 1860 1861 1866 |
between them; for 1869 1872 |
|
→ intermediate linking forms have not been discovered; 1859 1860 1861 1866 |
they cannot be closely connected; 1869 1872 |
|
→ is quite indefinite. 1859 1860 1861 1866 |
cannot be defined. 1869 1872 |
|
→ has been independently created. 1859 1860 1861 1866 |
are independent creations. 1869 1872 |
|
→ which 1859 1860 |
within each class which 1861 1866 1869 1872 |
|
→ vary most; 1859 1860 1861 |
yield the greatest number of va- rieties; 1866 |
yield the greatest number of varieties; 1869 1872 |
|
→for
two forms, if differing very little, are generally ranked as varieties, notwithstanding that
→intermediate linking forms have not been discovered;
but the amount of difference considered necessary to give to
forms the rank of species
→is quite indefinite. In genera having more than the average number of species in any country, the species of these genera have more than the average number of varieties. In large genera the species are apt to be closely, but
allied together, forming little clusters round
Species very closely allied to other species apparently have restricted ranges. In all these
respects the species of large genera present a strong analogy with varieties. And we can clearly understand these analogies, if species
once existed
varieties, and
thus
whereas, these analogies are utterly inexplicable if
species
→has been independently created.
|
|
We have, also, seen that it is the most flourishing
dominant species of the larger genera
→which
on an average
→vary most;
and varieties, as we shall hereafter see, tend to become converted into new and distinct species.
larger genera
tend to become larger; and throughout nature the forms of life which are now dominant tend to become still more dominant by leaving many modified and dominant descendants. But by steps hereafter to be explained, the larger genera also tend to break up into smaller genera. And thus, the forms of life throughout the universe become divided into groups subordinate to groups.
|