what steps the instinct of F. sanguinea originated I will not pretend
to conjecture. But as ants which are not slave-makers, will, as I have
seen, carry off pupae of other species, if scattered near their nests,
it is possible that such pupae originally stored as food might become
developed; and the foreign ants thus unintentionally reared would then
follow their proper instincts, and do what work they could. If their
presence proved useful to the species which had seized them--if it were
more advantageous to this species, to capture workers than to procreate
them--the habit of collecting pupae, originally for food, might by
natural selection be strengthened and rendered permanent for the
very different purpose of raising slaves. When the instinct was once
acquired, if carried out to a much less extent even than in our British
F. sanguinea, which, as we have seen, is less aided by its slaves than
the same species in Switzerland, natural selection might increase and
modify the instinct--always supposing each modification to be of use to
the species--until an ant was formed as abjectly dependent on its slaves
as is the Formica rufescens.

CELL-MAKING INSTINCT OF THE HIVE-BEE.

I will not here enter on minute details on this subject, but will merely
give an outline of the conclusions at which I have arrived. He must be
a dull man who can examine the exquisite structure of a comb, so
beautifully adapted to its end, without enthusiastic admiration. We
hear from mathematicians that bees have practically solved a recondite
problem, and have made their cells of the proper shape to hold the
greatest possible amount of honey, with the least possible consumption
of precious wax in their construction. It has been remarked that a
skilful workman, with fitting tools and measures, would find it very
difficult to make cells of wax of the true form, though this is effected
by a crowd of bees working in a dark hive. Granting whatever instincts
you please, it seems at first quite inconceivable how they can make
all the necessary angles and planes, or even perceive when they are
correctly made. But the difficulty is not nearly so great as at first
appears: all this beautiful work can be shown, I think, to follow from a
few simple instincts.

I was led to investigate this subject by Mr. Waterhouse, who has shown
that the form of the cell stands in close relation to the presence of
adjoining cells; and the following view may, perhaps, be