Se P t.,i 9 o8| Burrill: A Slave-making Foray. 145 



(Barrington Moore, Yale, '06 ; Robert Allen, Erie High School, '02 ; 

 and Daniel G. Saunders, Harvard, '04), had left behind them only- 

 three or four stragglers in a distance of over a rod of the rear trail, and 

 in the next ten minutes rushed on impetuously in a nearly straight 

 line for eighty-five feet more. 



The three or four stragglers could barely gain on the main column, 

 for the latter was going at breakneck speed, without any advance 

 guard or advance formation for driving in the enemy, as the sanguined 

 slave-makers do at a much lower rate of speed. Yet it was evident 

 that the ground passed over was as well covered by this flying de- 

 tachment as by the sanguineus with their mushroom -shaped advance, 

 two to four feet in width. Neither species has been seen to ascend 

 grass blades, but both swarm over flat leaves, low grass stubble, stones 

 and rubbish accumulations, without paying much attention to the 

 invasion of holes of nearby insects. Thus the stragglers were plunging 

 along, heads down, just as fast as couriers (or, perhaps, badly 

 frightened ants) ever go in the battles of the sanguineas, trying 

 almost vainly to catch up. 



The army passed directly over or across the edge of four hillocks 

 of a smaller common ant, resembling Prenolefis imparis. The latter 

 disappeared in their homes, and most of the swift-footed troop swept 

 over their hill-tops. Yet a few always lingered to dig the imparis out. 

 Thus four or five would set to work busily and excitedly excavating 

 for foes, but two or three minutes later I saw them speeding on after 

 the main troop. I surmise that the first stragglers I noticed may have 

 fallen behind by pursuing similar fruitless quests. But it would be* 

 just as likely that the army set off before these stragglers had climbed 

 out of the nest, and so were delayed in getting their bearings and 

 following the trail. It is certain that it would be more difficult for 

 belated ants of a Polyergus army to pick up the route than for san- 

 guineus, for the latter are always meeting friends along the way who 

 seem to act as an incitement to better speed, while these ants go in a 

 close formation with a rear as compact as the van, leaving no guides 

 en route, except scent. They seem to move just as close together as 

 they possibly can and yet keep up top speed, even closer than the 

 sanguineas, except when the latter are collecting in a crowd for the 

 main assault. 



Close to the goal, the army seemed to have come about a foot out 

 of line from the direct route they had been following, making allow- 



