with the rarest exception, hardly
ever lay fertile eggs. Many exotic plants have pollen utterly worthless,
in the same condition as in the most sterile hybrids. When, on the one
hand, we see domesticated animals and plants, though often weak and
sickly, breeding freely under confinement; and when, on the other hand,
we see individuals, though taken young from a state of nature perfectly
tamed, long-lived, and healthy (of which I could give numerous
instances), yet having their reproductive system so seriously affected
by unperceived causes as to fail to act, we need not be surprised at
this system, when it does act under confinement, acting irregularly,
and producing offspring somewhat unlike their parents. I may add that
as some organisms breed freely under the most unnatural conditions--for
instance, rabbits and ferrets kept in hutches--showing that their
reproductive organs are not easily affected; so will some animals
and plants withstand domestication or cultivation, and vary very
slightly--perhaps hardly more than in a state of nature.

Some naturalists have maintained that all variations are connected with
the act of sexual reproduction; but this is certainly an error; for I
have given in another work a long list of "sporting plants;" as they are
called by gardeners; that is, of plants which have suddenly produced a
single bud with a new and sometimes widely different character from that
of the other buds on the same plant. These bud variations, as they may
be named, can be propagated by grafts, offsets, etc., and sometimes
by seed. They occur rarely under nature, but are far from rare under
culture. As a single bud out of many thousands produced year after year
on the same tree under uniform conditions, has been known suddenly to
assume a new character; and as buds on distinct trees, growing
under different conditions, have sometimes yielded nearly the same
variety--for instance, buds on peach-trees producing nectarines, and
buds on common roses producing moss-roses--we clearly see that the
nature of the conditions is of subordinate importance in comparison
with the nature of the organism in determining each particular form of
variation; perhaps of not more importance than the nature of the spark,
by which a mass of combustible matter is ignited, has in determining the
nature of the flames.

EFFECTS OF HABIT AND OF THE USE OR DISUSE OF PARTS; CORRELATED
VARIATION; INHERITANCE.

Changed habits produce an inhe