country pretty freely under confinement, with the exception of the
plantigrades or bear family; whereas, carnivorous birds, with the
rarest exceptions, hardly ever lay fertile eggs. Many exotic plants
have pollen utterly worthless, in the same exact condition as in the
most sterile hybrids. When, on the one hand, we see domesticated
animals and plants, though often weak and sickly, yet breeding quite
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 in acting, we need not be surprised at
this system, when it does act under confinement, acting not quite
regularly, and producing offspring not perfectly like their parents or
variable.
Sterility has been said to be the bane of horticulture; but on this
view we owe variability to the same cause which produces sterility; and
variability is the source of all the choicest productions of the
garden. I may add, that as some organisms will breed most freely under
the most unnatural conditions (for instance, the rabbit and ferret kept
in hutches), showing that their reproductive system has not been thus
affected; so will some animals and plants withstand domestication or
cultivation, and vary very slightly perhaps hardly more than in a state
of nature.
A long list could easily be given of sporting plants; by this term
gardeners mean a single bud or offset, which suddenly assumes a new and
sometimes very different character from that of the rest of the plant.
Such buds can be propagated by grafting, etc., and sometimes by seed.
These sports are extremely rare under nature, but far from rare under
cultivation; and in this case we see that the treatment of the parent
has affected a bud or offset, and not the ovules or pollen. But it is
the opinion of most physiologists that there is no essential difference
between a bud and an ovule in their earliest stages of formation; so
that, in fact, sports support my view, that variability may be
largely attributed to the ovules or pollen, or to both, having been
affected by the treatment of the parent prior to the act of conception.
These cases anyhow show that variation is not necessarily connected, as
some authors have supposed, with the act of generation.
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