COMMUNICATING AND OTHER ANTS 75 



munication is equally true for any other faculty. 

 Harvesters have an acute sense of smell ; in other 

 ants it is almost absent. M. setipes detects by sight 

 the slightest movement, harvesters have a dim, 

 limited vision, other ants are totally blind. 



By communication these ants live ; it is the 

 mainspring of their existence. Could they not com- 

 municate they could neither capture their prey nor 

 overpower it and drag it to the nest. But is there 

 any real intelligence in this essential act of life ? I 

 could never see that there was. The ants were im- 

 pelled by a power far greater than their own feeble 

 minds ; they neither knew what they did nor did they 

 know why they did it. 



I have but few remarks to make on the remaining 

 species of ants that occur in this valley. A common 

 genus, Cremastogaster, which frequents the trunks of 

 the trees, has the peculiar habit of turning up its 

 heart-shaped abdomen so as to stand out at right 

 angles to the rest of the body. When the ant is 

 running about excitedly, the pointed and projecting 

 abdomen gives the insect a somewhat terrifying 

 appearance, and suggests that it is prepared to sting 

 savagely on the slightest provocation. As in the 

 case of the Myrmecocystus, I first considered that the 

 peculiar attitude adopted by this genus possessed 

 the useful function of suggesting to insectivorous 

 enemies that it was a ferocious creature and that they 

 had better abstain from attack. I doubt, however, if 

 this explanation is correct, for I have observed that 

 another species, Camponotus compressus, which does 

 not usually adopt this attitude, will, when descending 

 a tree-trunk head foremost, allow its abdomen to fall 



