See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1860
1861
1866
1869
1872

cases both of 1859 1860 1861 1866
instances of both 1869 1872

in most cases 1859 1860 1861 1866
OMIT 1869 1872

and therefore we might expect that such variability 1859 1860 1861 1866
which 1869 1872

be super-added to 1859 1861
be superadded to 1860 1866
be added to 1869
would augment 1872

cross or in the first 1859 1860 1861 1866
OMIT 1869 1872

their extreme variability in 1859 1860 1861 1866
that in 1872
OMIT 1869

on 1859 1860 1861 1866
of one of 1869 1872

it is due to 1859 1860 1861 1866
OMIT 1869 1872

being thus often rendered either impotent or at least incapable of 1859 1860 1861 1866
fails under these circumstances to perform 1869 1872

identical with 1859 1860 1861 1866
identical in all respects with 1869
closely similar in all respects to 1872

1 blocks not present in 1859 1860 1861; present in 1866 1869 1872
Moreover, Gärtner expressly states that hybrids from long-cultivated plants are more subject to reversion than hybrids from species in their natural state; and this probably explains the singular difference in the results arrived at by different observers: thus, Max Wichura doubts whether hybrids ever revert to their parent- forms, and he experimented on uncultivated species of willows; whilst Naudin, on the other hand, insists in the strongest terms on the almost universal tendency to reversion in hybrids, and he experimented chiefly on cultivated plants.

but some few cases both of hybrids and mongrels long retaining
a uniform
uniformity of
character could be given. The variability, however, in the successive generations of mongrels is, perhaps, greater than in hybrids.
This greater variability
in
of
mongrels than
in
of
hybrids does not seem
to me
to me
at all surprising. For the parents of mongrels are varieties, and mostly domestic varieties (very few experiments having been tried on natural varieties), and this implies in most cases that there has been recent
variability,
variability;
and therefore we might expect that such variability would often continue and be super-added to that arising from the
mere
mere
act of crossing. The slight
variability
degree
of
hybrids
variability
in
hybrids from
hybrids from
the first cross or in the first generation, in contrast with their extreme variability in the succeeding generations, is a curious fact and deserves attention. For it bears on
and corroborates
and corroborates
the view which I have taken on the
causes
cause
of ordinary
variability:
variability;
namely, that it is due to the reproductive system
from being
being
eminently sensitive to
any
any
changed
change
in the
in the
conditions of life, being thus often rendered either impotent or at least incapable of its proper function of producing offspring identical with the parent-form. Now hybrids in the first generation are descended from species (excluding those
long
long
long-cultivated)
cultivated)
which have not had their reproductive systems in any way affected, and they are not variable; but hybrids themselves have their reproductive systems seriously affected, and their descendants are highly variable.
But to return to our comparison of mongrels and hybrids: Gärtner states that mongrels are more liable than hybrids to revert to either parent-form; but this, if it be true, is certainly only a difference in degree. Gärtner further
states
insists
that when any two species, although most closely allied to each other, are