MICROSCOPIC BRAINS. 13 



degeneration, this high sense of smell has been 

 continued and further developed, till it has 

 become their principal sense-endowment, and 

 the chief raw material of their intelligence. 

 Their active little brains are almost wholly en- 

 gaged in correlating and co-ordinating smells 

 with actions. Their olfactory nerves give 

 them nearly all the information they can gain 

 about the external world, and their brains 

 take in this information and work out the 

 proper movements which it indicates. By 

 smell they find their way about and carry on 

 the business of their lives. Just as you and 

 I know the road from Regent's Circus to 

 Pall Mall by visible signs of the street-corners 

 and the Duke of York's Column, so these 

 little ants know the way from the nest to the 

 corpse of the dismembered worm by observ- 

 ing and remembering the smells which they 

 met with on their way. See : I obliterate 

 the track for an inch or two with my stick, 

 and the little creatures go beside themselves 

 with astonishment and dismay. They rush 



