and
manufactured
instruments,
a perfect
division
of labour
could be
effected
with them
only by
the
workers
being
sterile;
for had
they been
fertile,
they would
have
intercrossed,
and their
instincts
and
structure
would have
become
blended.
And nature
has, as I
believe,
effected
this
admirable
division
of labour
in the
communities
of ants,
by the
means of
natural
selection.
But I am
bound to
confess,
that, with
all my
faith in
this
principle,
