44 BRITISH ANTS. 



Forel has called a " contact-odour." Wasmann speaks of the 

 antennae as "touching-noses"; he says ants do not know each 

 other personally, but recognize each other by an intelligent 

 "parole," a recognized form of antennal stroke. Miss Fielde has 

 carried out a number of experiments to prove that each of the 

 different joints of an ant's antennae has a different function. For 

 example she considers the final joint recognizes the home or nest 

 odour, the penultimate recognizes personal relations, the ante- 

 penultimate the path or track, etc. She also concludes that the 

 whole nest aura changes every two or three months. Though 

 these experiments are very carefully elaborated, the results are 

 by no means conclusive ; the subject being far too difficult and 

 intricate to be settled so easily. It is certain however that if an 

 ant's antennae be removed it can neither find its food only feeding 

 if it accidentally stumbles on to it nor its way, nor recognize 

 friends from foes, etc. 



Ants possess great delicacy of touch tactile hairs and sensillae 

 being present all over the body, as well as on the antennae and 

 this sense is also of great importance to them. Their extreme 

 sensitiveness to light and temperature is probably closely con- 

 nected with their sense of touch. 



The sense of taste is situated in the tongue and maxillae. Ants 

 show distinct preferences for certain foods, and they quickly 

 detect any unpleasant substance even if odourless mixed with 

 their food. Wheeler considers that taste is evidently the sense in 

 which these insects approach most closely the higher animals 

 and man. 



Sight varies considerably in different species, some being com- 

 pletely blind. The exhibition of " mimicry " in certain myrme- 

 cophiles and parasitic ants, shows that their hosts possess the 

 power to discriminate colours and forms. Lubbock demonstrated 

 that ants can perceive, and avoid, the ultra-violet rays of the 

 spectrum, and Forel proved that this was through the eyes he 

 covered these organs with varnish, when the ants were no longer 

 able to distinguish these rays. Moving objects are more readily 

 observed by ants, but Wasmann has shown that certain species 

 can see an object not larger than a finger, at rest at a distance of 

 five to ten centimetres ; smaller objects, such as little beetles, cannot 

 be seen at a greater distance than four to five millimetres. I have 

 frequently observed a worker of Formica rufa when pursuing a small 

 beetle, will lose sight of it and run blindly by it. Exner's theory 

 that the compound eyes form of an object a single picture which is 

 more distinct the greater the number of facets possessed by these 

 eyes and the more convex they are, seems to be generally accepted. 

 In the case of the ocelli, however, it has been suggested that they 

 enable an ant to see better in the dark, but as they are largest and 

 best developed in the male who can see a flying female at some 



