| → 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
character could be given. The variability, however, in the successive generations of mongrels is, perhaps, greater than in hybrids. |
|
| This greater variability
mongrels than
hybrids does not seem
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
→and therefore we might expect that such variability
would often continue and
→be super-added to
that arising from the
act of crossing. The slight
of
in
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
the view which I have taken
→on
the
of ordinary
namely, that
→it is due to
the reproductive system
eminently sensitive to
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
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
that when any two species, although most closely allied to each other, are
|
