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[Vol. 90 
were closed. They were shortly released unharmed. The contrast 
with the B'-B" and B"-B' nest introductions could hardly have been 
more vivid. 
The same experiment was also carried out between the A and 
moieties. At 8:15 a.m. on November 18, 10 workers of A were 
introduced into the B" arena, again close to the nest entraces of B'\ 
Five minutes later there seemed complete compatibility. At 8:23 one 
worker was seen being dragged about, and at 8:25 two were being so 
treated. By 8:35 only one such pair was seen, and nothing further 
developed through the cessation of observations at 9:15 p.m. The 
results of all three of these experiments are summarized in Table I. 
One further confirmation of these results was required. Only three 
days had elapsed between the confrontation of nest B ' with that of 
B" in the B" arena, (when the B' colony was apparently occupied by 
the B" moiety) and the test introduction of ten B' workers into the 
B" arena. If (as seemed likely) the introduced B' nest had been 
occupied by B" workers, could not the passive reception of the new 
B' workers be attributed either to the presence of other B' workers in 
the arena or, alternatively (or in addition) might not B" workers 
have become somewhat adapted to B' odors, modifying their 
reaction? Though the introduced B' nest in the B" arena was 
removed after the “nest experiment” and before the new experiment 
with the ten B' workers, since but three days had elapsed between 
experiments, both factors might well have been involved. 
To check this, a longer time interval was allowed to intervene 
before the 10-worker test was repeated. On February 15, 1983, 92 
days after the preceding tests (all colonies having been left undis- 
turbed in the meantime) 10 workers of B" were again introduced to 
the B' arena, close to the stacked nests of B'. Introduction was made 
at 3:45 p.m. At 4:10 two workers were “clinched” and mutually 
stinging near a nest entrance. Five minutes later activity at the nest 
entrance was much diminished, and the stinging pair was not seen. 
At 4:12, and again at 4:30 p.m., general activity was much dimin- 
ished but two workers presumed “alien” were being dragged about 
the arena. At 4:35 p.m. no further hostility had developed, but one 
or two males had emerged from a B' nest. At 5:00 p.m. the arena was 
entirely quiet, with only two workers outside the nests. An hour 
later the situation was similarly quiet, but one “alien” worker was 
being dragged about the arena and two freshly killed workers were 
