414 INTRODUCTION TO ZOOLOGY CHAP. 



municate can hardly be doubted if they are watched, 

 especially on an occasion when one solitary ant having 

 found food returns to the nest, and apparently spreads the 

 news. 



Several different actions can be easily distinguished which 

 seem to have special significance. There is the gentle 

 stroking of the face of a forager by an ant supplicating 

 for food, the violent butting with the head and excited 

 waving of antennae when an ant hurries home after finding 

 a store of food, and many other gradations of movement of 

 the antennae, the significance of which is as yet obscure to us. 

 The sense of smell is also acute, and together 

 w ^ ^ e sense f touch seems concentrated in 

 special hairs on the antennae. As the latter are 

 waved about, probably the ant is learning as much about 

 its environment by the various odours it detects, as by the 

 actual touch impressions. Imagine how much more our 

 sense of smell would mean to us if we could smell with our 

 fingers, and thus be able to investigate the variations in the 

 odour of every crack and cranny of an object. Loss of keen- 

 ness of this sense is one of the disadvantages of the upright 

 position, which in other ways has given man so many advan- 

 tages over the lower animals, who, however, with their heads 

 down, can sniff out the messages of the ground which are 

 lost to us. It is probably by this keen sense of smell and 

 power of discriminating odours that ants distinguish their 

 friends from their foes; ants removed from a nest are 

 recognised and welcomed after months of absence. 



Besides possessing special sense organs, it is also neces- 

 sary for the brain to be sufficiently developed to interpret 

 the sensation received, and we find that whilst the worker 

 ants seem to learn much from, and depend much upon, 

 this special " contact-odour " sense, as it has been called, 1 

 the male ants, with the same sense organs but far smaller 

 brains, are exceedingly stupid, and are unable to distinguish 

 friends from enemies, or to find their way back to the nest 

 if they stray from it. 



The sense of taste seems to be located in 

 cer ^ am sensory hairs found round the mouth on 

 the soft jaws and lower lip with its palps. 

 1 Forel, Ants and some other Insects. 



