| → possess 1872 |
| supposed to have been created independently, have 1859 1860 1861 1866 1869 |
|
| → possessed 1872 |
| the species of the genus have 1859 1860 1861 1866 1869 |
|
| → tropical and temperate South 1866 1869 1872 |
| South 1859 1860 1861 |
|
|
the species of the same genus differ from each other, be more variable than
generic characters in which they all agree? Why, for instance, should the colour of a flower be more likely to vary in any one species of a genus, if the other
→possess
differently coloured flowers, than if all
→possessed
the same coloured flowers? If species are only well-marked varieties, of which the characters have become in a high degree permanent, we can understand this fact; for they have already varied since they branched off from a common progenitor in certain characters, by which they have come to be specifically distinct from each other;
therefore these same characters would be more likely
to
than the generic characters which have been inherited without change for an
period. It is inexplicable on the theory of creation why a part developed in a very unusual manner in
one species
a genus, and therefore, as we may naturally infer, of great importance to
species, should be eminently liable to variation; but, on
view, this part has
since the several species branched off from a common progenitor, an unusual amount of variability and modification, and therefore we might expect
part generally to be still variable. But a part may be developed in the most unusual manner, like the wing of a bat, and yet not be more variable than any other structure, if the part be common to many subordinate forms, that is, if it has been inherited for a very long period; for in this case it will have been rendered constant by long-continued natural selection. |
|
| Glancing at instincts, marvellous as some are, they offer no greater difficulty than
corporeal
on the theory of the natural selection of successive, slight, but profitable modifications. We can thus understand why nature moves by graduated steps in endowing different animals of the same class with their several instincts. I have attempted to show how much light the principle of
throws on the admirable architectural powers of the hive-bee. Habit no doubt
comes into play in modifying instincts; but it certainly is not indispensable, as we
in the case of neuter insects, which leave no progeny to inherit the effects of long-continued habit. On the view of all the species of the same genus having descended from a common parent, and having inherited much in common, we can understand how it is that allied species, when placed under
different conditions of life, yet
follow nearly the same instincts; why the
of
→tropical and temperate South
America, for instance,
with mud like our British species. On the view of instincts having been slowly acquired through natural
we need not marvel
|
