proves
that with
animals,
as with
plants,
any amount
of
modification
in
structure
can be
effected
by the
accumulation
of
numerous,
slight,
and as we
must call
them
accidental,
variations,
which are
in any
manner
profitable,
without
exercise
or habit
having
come into
play. For
no amount
of
exercise,
or habit,
or
volition,
in the
utterly
sterile
members of
a
community
could
possibly
have
affected
the
structure
