140 THE SOCIAL LIFE OF ANIMALS 



with different individuals. If marked ants, whose 

 reaction time has been tested in isolation, are placed 

 together in pairs or in groups, they will start work 

 sooner and will work with greater uniformity than 

 if alone. 



With oriental patience. Professor Chen and his 

 assistants collected and counted the number of the 

 tiny pellets of earth which were dug by different 

 individual ants when isolated, and when members 

 of groups of two or three ants. They found that the 

 number of pellets removed is greater when the ants 

 work in association with others than when each 

 works alone. This accelerating effect is greater for 

 slow than for rapid workers; when ants with inter- 

 mediate working tendencies were tested (Figure 25) 

 they were found to be speeded up when in com- 

 pany with a rapid co-worker and relatively retarded 

 when placed with a slowly working ant. Interestingly 

 enough, there was no difference between the stimu- 

 lating effect of one additional ant and of many ants 

 on the rate of work of a given individual. The social 

 facilitation seemed maximum for these digging tests 

 when only a second individual was present. 



Ants which regularly work rapidly were found to 

 be physiologically different from those that work 

 more slowly. The faster workers were more suscepti- 

 ble to starvation, to drying, and to exposure to ether 



