AGRICULTURAL ANTS 



gravel piled around the gate, which apparently have 

 been brought up from the excavated galleries and 

 granaries underneath. Occasionally one sees a decided 

 truncated cone raised in the centre of a circle, with the 

 gate piercing the dish-shaped top. 



Another striking variation appears. Most of the flat 

 disks are wholly without vegetation, but here and there 

 are nests whose circular pavement around the gate has 

 a bortlering band covered with two species of grass, 

 Aristida oligantha and Aristida stricta, known as ant- 

 rice, or, more popularly, needle-grass. That this is per- 

 mitted by the ants is plain. No other plant is thus 

 tolerated, and their seeds are gathered and stored with 

 others in the undergromid granaries. Moreover, it is 

 quite within the ants' power to keep their disks clean. 

 They were often found established in a thicket of wild 

 sage, daisy, and other vigorous weeds, with stalks as 

 thick as one's thumb and standing several feet high. 

 This rank growth, quickened by the fat soil and semi- 

 tropical sun, is as thoroughly under the control of our 

 Barbati as are the cleared fields amid the woods under 

 the settlers' control. Not a plant is allowed to intrude 

 upon the formicary bounds; and, although often seen, 

 it was an interesting sight, after pushing through the 

 high weeds, to come upon one of these nests, and ob- 

 serve the tall, tough vegetation standing in a wellnigh 

 perfect circle around the edge of the clearing. The 

 weeds had crowded up as closely as they dared, and 

 were held back from the forbidden grounds by the 

 insects, whose energy and skill could easily limit their 

 bounds. Certainly, ants capable of such work could 

 readily have cleared away growing stalks of the Aristida, 

 In fact, after the seed has ripened in the late summer 



87 



