xxvi INSECTA : HYMENOPTERA 415 



Undoubtedly ants have a decided predilection for one food 

 over another. 



Many experiments have been carried out with 



different kinds of ants which seem to su gg est that 

 they certainly remember. Forel describes how 

 an ant, having found a good spot for a new nest, perhaps 

 30 metres from the old nest, returned, and seizing a sister 

 ant, carried her back with her straight to the spot, evidently 

 remembering the desired goal of her excursion. Even more 

 conclusive are the observations which have been made on 

 the red slave-making ants, Polyergus (see p. 418). These 

 ants, led by " scout " ants who have been exploring the 

 ground before, go some distance to raid the nest of the little 

 black ant, Formica fusca, and carry off the larvae and pupae 

 to their own nest. If the black ants' nest is cleared at the 

 first raid, the slave-makers do not return to it, but if 

 some of the brood be left behind, they will return on the 

 same or the next day to carry it off, suggesting that their 

 action is due to their memory of the spoil left behind on 

 the first raid. 



Also it has been shown that some ants can be trained 

 to come and feed off the finger, or to make use of an artificial 

 bridge placed over a water moat round their island nest, and 

 that individuals vary greatly in the ease with which they 

 can be thus taught. 1 



From these and other observations and experiments it 

 appears obvious that ants learn by experience, and possess 

 some kind of memory ; but possibly this is merely a matter 

 of association of sensory impressions, and no power of re- 

 calling facts may exist apart from this sensory stimulus. 

 That ants have true recollection, or that they have any 

 power of reasoning, is as yet not demonstrated, though this 

 has often been claimed for them by investigators. 



They certainly sometimes exhibit a decided individuality, 

 as indicated by the individual dislikes they show. For 

 example, one ant in a colony kept by Forel cherished an 

 antipathy for another ant of an adjacent colony kept on the 

 same table. Three times this ant seized its hated neighbour 

 and threw it over the precipice of the table edge, the perse- 

 cuted ant being each time picked up and replaced by M. Forel. 

 1 Cp. G. Turner's experiments quoted by Wheeler in Ants, p. 537. 



