It It 1869 1872 |
With respect to the effects of this intercrossing, it 1860 1861 1866 |
should be
borne in mind borne in mind 1869 1872 |
remembered 1860 1861 1866 |
that the offspring of such crosses would almost
certainly gain in vigour; so that even an occasional cross would produce more effect than might
....... 1869 1872 | at first 1860 1861 1866 |
have been have been 1860 1869 1872 | be 1861 1866 |
anticipated.
I will I will 1869 1872 | To 1860 1861 1866 |
give a few
illustrations of the foregoing remarks: illustrations of the foregoing remarks: 1869 1872 |
examples: 1860 1861 1866 |
in the Galapagos Islands nearly every land-bird, but only two out of the eleven marine birds,
are peculiar;
and it is obvious that
marine birds
only 2 are peculiar; and it is obvious that marine birds could only 2 are peculiar; and it is obvious that marine birds could 1861 1869 1872 |
could 1860 |
only 2 are peculiar; and it is obvious that marine birds only 2 are peculiar; and it is obvious that marine birds could 1866 |
arrive at these islands
much more easily and frequently much more easily and frequently 1869 1872 |
more easily 1860 1861 1866 |
than land-birds. ↑1 blocks not present in 1860 1861 1866 1869 1872; present in 1859 | Thus in the Galapagos Islands nearly every land-bird, but only two out of the eleven marine birds, are peculiar; and it is obvious that marine birds could arrive at these islands more easily than land-birds.
|
Bermuda, on the other hand, which lies at about the same distance from North America as the Galapagos Islands do from South America, and which has a very peculiar soil, does not possess
a single endemic land-bird; a single endemic land-bird; 1869 1872 |
one endemic land bird; 1859 |
one endemic land-bird; 1860 1861 1866 |
and we know from Mr. J. M.
Joness Joness 1869 | Jones's 1859 1860 1861 1866 1872 |
admirable account of Bermuda, that very many North American birds,
occasionally or even frequently visit occasionally or even frequently visit 1869 1872 |
during their great annual migrations, visit either periodically or occasionally 1859 1860 1861 |
occasionally visit 1866 |
this island. Almost every year, as I am informed by Mr. E. V. Harcourt, many European and African birds are blown to Madeira; this island is inhabited by 99 kinds, of which one alone is peculiar, though very closely related to a European form; and three or four other species are confined to this island and to the Canaries. ↑1 blocks not present in 1866 1869 1872; present in 1859 1860 1861 | Madeira does not possess one peculiar bird, and many European and African birds are almost every year blown there, as I am informed by Mr. E. V. Harcourt.
|
So that
the the 1869 1872 | these two 1859 1860 1861 | the two 1866 |
islands
of Bermuda and Madeira have been stocked
from the neighbouring continents with from the neighbouring continents with 1869 1872 |
by 1859 1860 1861 1866 |
birds, which for long ages have
struggled together, and struggled together, and 1869 |
struggled together in their former homes, and have 1859 1860 1861 1866 |
there struggled together, and have 1872 |
become mutually
adapted; hence when settled in their new homes, each kind would be kept by the others to its proper place and habits, and would consequently be but little liable to modification. adapted; hence when settled in their new homes, each kind would be kept by the others to its proper place and habits, and would consequently be but little liable to modification. 1869 |
adapted to each other; and when settled in their new homes, each kind will have been kept by the others to their proper places and habits, and will consequently have been little liable to modification. 1859 1860 1861 |
adapted to each other; and when settled in their new homes, each kind will have been kept by the others to its proper place and habits, and will consequently have been little liable to modification. 1866 |
co-adapted. 1872 |
Any tendency to modification
would would 1869 | will, 1860 | will 1861 1866 1872 |
also,
be be 1869 | have been 1860 1861 1866 1872 |
checked by intercrossing with the unmodified immigrants
from
the mother-country. ↑1 blocks not present in 1859 1860 1861 1866 1869; present in 1872 | Hence when settled in their new homes, each kind will have been kept by the others to its proper place and habits, and will consequently have been but little liable to modification.
|
Madeira,
again,
is inhabited by a wonderful number of peculiar land-shells, whereas not one species of sea-shell is confined
to its
|