56 THE INDUSTRIES OF ANIMALS. 



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 re.sult 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 neigh- 

 bourhood 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 antennas 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 Fonidca fusca. The 

 alarm is immediately given in the threatened ant-hill; 



