276 I.V7.V. 



sets about IKT work in a most methodical way. The workers never 

 forage individually for grain, hut all take the same road and all return 

 by the same road : the result being that every nest is the starting point 

 of one. or often of several, well-beaten tracks, cleared of vegetation and 

 obstacle-, and extending sometimes 100 feet and more in length. How 

 these tracks are engineered I have never discovered, but am pretty cer- 

 tain that the\ are made gradually; a commencement at hazard is made, 

 and then, as the country immediately adjoining the road is exploited, 

 the road itself is carried forward. Where one of these roads crosses a 

 >heet of bare rock, it is there marked in white; I can only presume that 

 this is the result of some chemical action, set up by the formic acid 

 exuding from the ants ; this acid, though too small in quantity in a 

 single ant to cause any appreciable effect, might easily become sufficient 

 when thousands of ants are continually passing, backwards and for- 

 wards, all day long. Holcomyrmex brings home the grain unthreshed, 

 and, in this form, it is taken into the nest, from whence the chaff is 

 brought out and deposited around the entrance, or, where the force of 

 a prevalent wind is felt, on a heap to leeward." Wroughton does not 

 believe that H. scabriccps, which Rothney regards as the harvester par 

 excellence of India, compares with Pheidolc as a harvester. 



The following note on Phcidoloycton ocellifer, an ant with highly 

 polymorphic workers, was communicated to Wroughton by Aitken : 

 ' The entrance (of the nest ) which is strewn with chaff, is large, but 

 the passage soon splits up, and I failed to follow it. I turned up a lot 

 of pupae, however, close to the surface. The community is enormous 

 and industrious, collecting large seeds of trees or plants, which it takes 

 a dozen to carry ; these are taken in and the husks are thrown out after- 

 wards. If P. ocellifer meets a white ant or any other insect, she col- 

 lects it in the same way. The smaller soldiers often laid a jaw to a 

 burden, but the giants appear to do nothing." Wroughton confirms this 

 observation on the carnivorous tastes of Pheidologeton. He found 

 also that the huge soldiers neither dig nor defend the nest and that they 

 are less pugnacious than the smaller workers. It is probable that they 

 function as seed crushers like the soldiers of the allied genus Pheidolc. 

 Arm it (1878), Roth (1885) and Tryon (1900) have published a 

 few observations on harvesting ants in another arid or semiarid region, 

 Australia. These are Pheidolc longiceps, Mcranoplns diniidicttns and 

 .17. dri'crsus. Tryon calls attention to the seed-distributing habits of 

 the Pheidolc in the following passages: " That this Brisbane harvesting 

 ant, also, is an important agent in the local dispersion of plants espe- 

 cially weeds and is connected with their sudden appearance on heaps 

 of soil excavated from a depth, is sufficiently demonstrated in the fol- 



