See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1861
1866
1869
1872

not of differences in the reproductive system. 1859 1860 1861 1866
that they have not been long exposed to uniform conditions of life. 1869 1872

1 blocks not present in 1859 1860 1861; present in 1866 1869 1872
Nor should it be forgotten that long-continued domestication apparently tends to eliminate sterility, and is therefore little likely to induce this same quality.

In 1859 1860 1861
Excluding the subject of fertility, in 1866

the facts briefly 1859 1860
although we are profoundly ignorant in every case of the precise cause of sterility, the facts briefly 1861
although we are profoundly ignorant in every case of the precise cause of the sterility of first crosses and of hybrids, the facts briefly 1866
although we are profoundly ignorant of the precise cause of the sterility of first crosses and of hybrids, the facts 1869
although we are as ignorant of the precise cause of the sterility of first crosses and of hybrids as we are why animals and plants removed from their natural conditions become sterile, yet the facts 1872

to, but even rather to support the view, that there is no fundamental distinction between species and varieties. 1859 1860
to, but even rather to support in some respects the view, that there is no fundamental distinction between species and varieties. 1861
to the view, that there is no fundamental distinction between species and varieties. 1866
to the belief that varieties and species are not fundamentally different. 1869
to the belief that species aboriginally existed as varieties. 1872

fertile. Nor is this
almost universal
nearly general
and perfect fertility surprising, when
it is
we
remembered
remember
how liable we are to argue in a circle with respect to varieties in a state of nature; and when we remember that the greater number of varieties have been produced under
domesti- cation
domestication
by the selection of mere external differences, and not of differences in the reproductive system. In all other
respects
respects,
excluding fertility,
excluding fertility,
there is
the
a
closest
close
general resemblance between hybrids and mongrels. Finally, then, the facts briefly given in this chapter do not seem to me opposed to, but even rather to support the view, that there is no fundamental distinction between species and varieties.