5 ra e 20 25 30 35 40 45 50 55 60 5 10 15 20 25 30 35 40 45 50 55 60 

 TIME IS MINUTES 



Fig. 25. An ant which works at an intermediate rate 

 (Ml) may be speeded up if placed with an ant which 

 works more rapidly (Rl) and slowed down if put with a 

 slower worker (SI). (From Chen.) 



