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See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1869
1872

→ does not diminish, but is apt to increase; this increase being perhaps intelligible, as before explained, on the principles of inheritance and from too close interbreeding. 1866
rarely diminishes. 1859 1860 1861
does not diminish; it is even apt to increase, this being generally the result, as before explained, of too close interbreeding. 1869 1872
→ so like in every respect to that of hybrids, 1866
OMIT 1872
(as will be immediately explained) 1869
→ of 1866
OMIT 1872
when individuals belonging to 1869
→ species (as will be immediately described), 1866
OMIT 1872
form are united, 1869
↑ 1 blocks not present in 1859 1860 1861 1866 1872; present in 1869
It should, however, be borne in mind that the sterility of these plants has been acquired for a special purpose, and may differ in origin from that of hybrids.
→ this or any other view, 1866
vague hypotheses, 1859 1860 1861
the above or any other view, 1869 1872
→ or constitution having 1866 1869
having 1859 1860 1861 1872
→ It may seem fanciful, but I suspect that a 1859 1860 1861 1866
A 1869 1872
→ extends to 1859 1860 1861 1866
apparently extends to 1869
holds good with 1872
→ that 1859 1860 1861 1866 1869
which I have elsewhere given, that 1872
→does not diminish, but is apt to increase; this increase being perhaps intelligible, as before explained, on the principles of inheritance and from too close interbreeding. The above view of the sterility of hybrids being caused by two
different
different
constitutions
being
having been
compounded
confounded
into one has
lately
lately
been strongly maintained by Max
Wichura.
Wichura;
but
but
it
it
must
must
be
be
owned
owned
that
that
the
the
sterility
sterility,
sterility,
→so like in every respect to that of hybrids,
which
which
affects
affects
the
the
offspring
illegitimate offspring
illegitimate offspring
of
of
dimorphic
dimorphic
and
and
trimorphic
trimorphic
plants,
plants
plants
→of
the
the
same
same
→species (as will be immediately described),
makes
makes
this
this
view
view
rather
rather
doubtful.
doubtful.
↑
It
must,
must
however,
also
also
be
confessed
owned
that we cannot understand,
excepting
except
....
on →this or any other view, several facts with respect to the sterility of hybrids; for instance, the unequal fertility of hybrids produced from reciprocal crosses; or the increased sterility in those hybrids which occasionally and exceptionally resemble closely either pure parent. Nor do I pretend that the foregoing remarks go to the root of the
matter;
matter:
no explanation is offered why an organism, when placed under unnatural conditions, is rendered sterile. All that I have attempted to
show
show,
is,
is
that in two cases, in some respects allied, sterility is the common
result,—
result, —
result,—in
in
....
the one case from the conditions of life having been disturbed, in the other case from the organisation →or constitution having been disturbed by two organisations
having been
being
compounded into one.
→It may seem fanciful, but I suspect that a similar parallelism →extends to an allied yet very different class of facts. It is an old and almost universal
belief
belief,
founded
founded,
I think,
I think,
on a considerable body of evidence, →that slight changes in the conditions of life are beneficial to all living things. We see this acted on by farmers and gardeners in their frequent exchanges of