dublin] SLAVE-MAKING HABITS OF ANTS 139 



the fusca nests and soon dispense with slavery altogether. These 

 are eases of temporary slavery in which the mixed condition is 

 resorted to only during the most critical period of the foundation 

 of the colony. It may therefore, be concluded that these 



slave-makers show but little ill effect from the habit. Although 

 they may in this way reap a considerable advantage in their 

 struggle for existence, they are as yet in no sense dependent upon 

 their slaves. The slave-making instinct itself is in this species 

 in an unfixed or formative condition. 



Much further advanced is the slave-making habit in the 

 related Amazon ants, represented in Europe by Polyergus 

 rutescens, (Fig. 2 a) and in America by the so-called shining 

 slave-maker Polyergus lucidus and some other related varieties. 

 It is safe to say that among these Amazons no slaveless colonies 

 exist, so far has this instinct progressed among them. The 

 colonies begin in much the same way as among the sanguinaries, 

 a young fertilized queen being most probably adopted in a 

 queenless or weakened Formica fusca (Fig. 2c.) or F. rufibarbis 

 colony. With the advance of the season and multiplication of 

 Amazons the number of slaves is maintained and even increased 

 through the robbery of the neighboring nests of these little 

 black ants. The plundering is on a much larger scale than 

 in the preceding instance. Forel, to whom more than to anv 

 other observer we owe our knowledge of these forms, calculated 

 that a single colony in the course of one summer captured as 

 many as forty thousand larva? and pupae of the unfortunate 

 slaves. Indeed this seems to be the only activity of the ants of 

 this species of Polygerus. 



Nothing can be more fascinating than these slave-robbing 

 expeditions. Thus, to quote a well known description from 

 Forel : 



"One afternoon at half past three o'clock, the Amazons of a large nest 

 located in a meadow ten steps from a path drew out in a direction at right 

 angles to it; after they had gone obliquely a little, they took the straight path 

 again. Finally, I discovered at a distance of two steps from the army a nest 

 that was covered with Rufibarbis which was at a distance of fifty steps from 

 the Amazon nest. The vanguard of the armv recognized that thev had 

 reached their destination while they were as yet one decimeter from the Rufi- 

 barbis; for they suddenly stopped and sent a crowd of emissaries which with 

 incredible haste rushed back into the main bodv and the rear guard of the 



