THE ANTS OR PISMIRES 



Some ants living on trees tap the leaves with their heads 

 as a danger signal. When a number of workers do this 

 simultaneously a clearly audible sound is produced ; but this 

 can hardly be more than a generalised signal, like the blowing 

 of a policeman's whistle. Other ants are able to produce 

 a slight sound by rubbing together the roughened surfaces 

 of two overlapping parts of the abdomen. This appears to 

 be used as a danger signal, but it seems unlikely that it 

 conveys any very precise information : some information 

 is also conveyed in the exchanges of food which are such a 

 regular feature of the ant-colony. A single worker bringing 

 in a crop full of Aphis-excretions shares it out with many of 

 the nurses inside the nest. A worker may also solicit another 

 worker for food, standing face to face and tapping or strok- 

 ing the other with her antennae. Clearly the donation of food 

 at least conveys the information that such food is available 

 at some point outside the nest. Conversely, the eagerness 

 with which food is demanded, depending on the state of the 

 grubs as well as on that of the adults, conveys to the foraging 

 workers information on the needs of the whole colony. But 

 it has not yet been possible to detect the communication of 

 precise information, either on the location of food or on 

 the needs of the colony. In recent years, however, a good 

 deal has been learnt of how ants find their way, and this bears 

 on the method by which a worker stimulated to start foraging 

 might successfully find a source of food already discovered 

 by other workers. After all, even the marking of a trail 

 involves a simple form of language. 



TRAIL-MAKING AND PATH-FINDING 



As might be expected, there are considerable differences 

 between different kinds of ants : many of them, though 

 rather versatile, tend to use one type of information more 



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