See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1869
1872

advanced by me 1860 1861 1866 1869 1872
entertained 1859

and by Mr. Wallace in the Linnean Journal, 1860 1861 1866 1869
on the origin of species, 1859
and by Mr. Wallace, 1872

on the origin of species are 1860 1861 1866 1869 1872
are 1859

in essence a 1859 1860 1861 1866
a true 1869 1872

OMIT 1866 1869 1872
as with the primrose and cowslip; 1859 1860 1861

When the views advanced by me in this
volume
volume,
and by Mr. Wallace in the Linnean Journal, or when analogous views on the origin of species are generally admitted, we can dimly foresee that there will be a considerable revolution in natural history. Systematists will be able to pursue their labours as at present; but they will not be incessantly haunted by the shadowy doubt whether this or that form be in essence a species.
This,
This
I feel
sure
sure,
and I speak after experience, will be no slight relief. The endless disputes whether or not some fifty species of British brambles are
good
true
species will cease. Systematists will have only to decide (not that this will be easy) whether any form be sufficiently constant and distinct from other forms, to be capable of definition; and if definable, whether the differences be sufficiently important to deserve a specific name. This latter point will become a far more essential
con-
....
sideration
consideration
than it is at present; for differences, however slight, between any two forms, if not blended by intermediate gradations, are looked at by most naturalists as sufficient to raise both forms to the rank of
species.
species.
Hereafter we shall be compelled to acknowledge that the only distinction between species and well-marked varieties is, that the latter are known, or believed, to be connected at the present day by intermediate gradations, whereas species were formerly thus connected. Hence, without
quite
....
rejecting the consideration of the present existence of intermediate gradations between any two forms, we shall be led to weigh more carefully and to value higher the actual amount of difference between them. It is quite possible that forms now generally acknowledged to be merely varieties may hereafter be thought worthy of specific
names,
names;
OMIT and in this case scientific and common language will come into accordance. In short, we shall have to treat species in the same manner as