92 MENTAL EVOLUTION IN MAN. 



invading multitude. Or, if the nest of any other species of 

 ant is found, a similarly strong force — or perhaps the whole 

 army — is deflected towards it, and with the utmost energy the 

 innumerable insects set to work to sink shafts and dig mines 

 till the whole nest is rifled of its contents. In these mining 

 operations the ants work with an extraordinary display of 

 organized co-operation ; for those low down in the shafts do 

 not lose time by carrying up the earth which they excavate, 

 but pass the pellets to those above ; and the ants on the sur- 

 face, when they receive the pellets, carry them — with an 

 appearance of forethought which quite staggered Mr. Bates — 

 only just far enough to insure that they shall not roll back 

 again into the shaft, and, after depositing them, immediately 

 hurry back for more. But there is not a rigid (or merely 

 mechanical) division of labour : the work seems to be performed 

 by intelligent co-operation amongst a host of eager little 

 creatures ; for some of them act at one time as carriers of 

 pellets, and at another as miners, while all shortly afterwards 

 assume the ofiice of conveyers of the spoil." * 



Mr. Belt writes : — " The Ecitons and most other ants 

 follow each other by scent, and I believe they can communi- 

 cate the presence of danger, of booty, or other intelligence to 

 a distance by the different intensity or qualities of the odours 

 given off. I one day saw a column running along the foot of 

 a nearly perpendicular tramway cutting, the side of which 

 was about six feet high. At one point I noticed a sort of 

 assembly of about a dozen individuals that appeared in 

 consultation. Suddenly one ant left the conclave, and ran 

 with great speed up the perpendicular face of the cutting 

 without stopping. . . . On gaining the top of the cutting, 

 the ants entered some brushwood suitable for hunting. In a 

 very short time the information was communicated to the 

 ants below, and a dense column rushed up in search of prey." 

 Again, Mr. Bates writes : — " When I interfered with the 

 column, or abstracted an individual from it, news of the 

 disturbance was quickly communicated to a distance of several 



• Animal Inteliigefice, pp. I14-116. 



