NATURE'S CRAFTSMEN 



{111(1 crowding into the gates or circular openings that 

 skirt the base are two columns of workers. Their fel- 

 lows hover around the doors, bent upon their several 

 duties. But these columns keep up a steady march 

 and countermarch without visible diminution of num- 

 bers, and without cessation day or night. One column 

 stretches off to the southwest, and disappears at in- 

 tervals under flat stones. It reappears, crosses the 

 tops of similar stones, intersects the lines of workers 

 busy about the surrounding hills, and penetrating the 

 jungle of grass beyond, is finally distributed among a 

 number of young trees not far distant. The other 

 column leads off in a straight line to the southeast for a 

 distance of eight rods to a large oak-tree which stands 

 by a stone wall that parts the wood tract containing the 

 "ant city" from a field. Leaving the well-marked road 

 at the foot of the oak, the column stretches along the 

 trunk and is distributed among the branches. 



A portion leads off upon one of the lower limbs, which 

 overhangs the stone fence. Stand atop of the wall and 

 look carefully among the twigs and branchlets. You 

 have the key to the movements of the promenaders upon 

 the avenue beneath. 



At various points vast numbers of aphids are clus- 

 tered. They clasp the branches with their feet. Their 

 abdomens are slightly elevated, their heads are depress- 

 ed, and their beaks, which are a sort of suction-pump, 

 pierce the tender bark, and tap the sweet sap coursing 

 within. This is the natural food of aphids, and appears 

 to undergo some change in transit through them that 

 adds to its toothsomeness. But what has this to do 

 with our ants ? Wait. Note this worker. It approaches 

 an aphid and fixes its attention upon the apex of the 



43 



