No doubt some organs may vary in three or
perhaps more directions, as in the length, breadth, thickness, or
curvature of the bill. But these may be taken as separate variations,
each of which again occurs as "more" or "less"; and thus the "right" or
"beneficial" or "useful" variation must always be present so long as any
variation at all occurs; and it has not yet been proved that in any
large or dominant species, or in any part, organ, or faculty of such
species, there is no variation. And even were such a case found it would
prove nothing, so long as in numerous other species variation was shown
to exist; because we know that great numbers of species and groups
throughout all geological time have died out, leaving no descendants;
and the obvious and sufficient explanation of this fact is, that they
did _not_ vary enough at the time when variation was required to bring
them into harmony with changed conditions. The objection as to the
"right" or "beneficial" variation occurring when required, seems
therefore to have no weight in view of the actual facts of variation.
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