44 
Psyche 
[ JUNE-SEPTE MBEU 
colonies. When waves of excitement caused by a continuing 
stimulus at a single locus inside the nest are measured, 
a pattern of alternating expansion and contraction through 
the linear galleries is noted. The maximum range of the 
wave expansions is a function of the magnitude of the 
stimulus. During the first several minutes the maximum 
range achieved by successive waves tends to be stable. 
This is evidently due to the fact that expansions are ordin- 
arily led by no more than one or two workers that break 
away momentarily from the zone of continuous excitement 
close to the stimulus ; these individuals run outward, creat- 
ing lesser, shorter-lived excitement among workers they 
pass, then turn back in the inevitable looping pattern that 
characterizes alarm behavior. After several minutes the 
workers in the zone of continuous excitement begin to adapt 
Figure 1. Spread of excitation through a laboratory colony of 
Pogonomyrmex badius. The continuing stimulus' in this instance was 
an injured, immobile Camponotus pennsylvanicus (DeGeer) worker pinned 
to one spot in the nest interior. The maximum range of excitation was 
measured at five-second intervals in one direction only outward from 
the stimulus through the linear galleries of the artificial nest. Nest 
temperature: 30° ± 2° C. Further explanation in the text. 
