necessary in fact to attack beings
nearly equally well endowed from an intellectual and physical point of
view. The enterprise evidently presents every possible difficulty; but
in case of success, the result more than compensates for the effort.
The master in future need not trouble to work, for he possesses a tool
capable of doing everything as well as himself, since by means of
language he can easily impress his will on the acts of the other; a
domestic animal is only an auxiliary, the slave entirely replaces his
owner in every labour.

Several species of ants thus obtain slaves. The best known of these is
the _Polyergus rufescens_. We shall see in another chapter in what way
they take advantage of slaves, and what relations they have with them.
At present it is only necessary to say how the slaves are obtained.
The expeditions organised for this purpose are simply a perfected
chase, both by the way in which they are conducted, and by the result
to which they are to lead. It is not a question of brutally seizing a
prey to be devoured immediately. The captured animal must be carefully
managed, carried away alive and in such a condition that it has not
yet known a free life, and can accustom itself to new conditions. When
the _Polyergus_ or Amazon ants desire to increase their band of
slaves, one first remarks extreme excitement in the neighbourhood of
the nest. They all come out helter-skelter, but this disorder lasts
only for a short time; they soon form in line, and a regular serried
column is formed, longer or shorter according to the swarm; it has
been found to measure more than five metres long by fifteen
centimetres broad. The Amazons advance, often changing their direction
like a dog who is seeking a scent: this is exactly what they are
doing, they smell the ground with their antennae in order to recognise
traces of the _Formica fusca_. In this march the eminently republican
instinct of the ants comes out. The band has no chief; those who are
at the head go forward smelling the ground; this slackens their pace,
so that they are passed by those in the ranks behind. Little by little
they fall into single file, and this continuing during the whole
course of the march, a particular ant may sometimes be at the head of
the column, sometimes in the middle, sometimes in the rear. At the end
of a longer or shorter period the expedition discovers a scent, which
it follows up to the nest of the _Formica fusca_. The alarm i