48 
Psyche 
[June-September 
The above observations show that the mandibular gland 
secretion from a single worker is adequate of itself to 
release alarm behavior. The social excitation waves charac- 
terizing alarm behavior in Pogonomyrmex badius are 
evidently propagated by means of excited workers exposing 
other workers to the secretion as they dash outward in 
their looping movements- Since the active component of 
the secretion is highly volatile, mass excitation tends 
quickly to die down when the primary external stimulus is 
removed. Finally, it is interesting to note that workers 
suddenly killed by predators under natural conditions are 
still capable of producing the alarm effect, since their 
secretion will be released when the head is crushed. One 
is reminded of the observation made commonly by students 
of ants (e.g., Carthy, 1951; Sudd, 1957) that crushed 
workers induce alarm or avoidance behavior in their nest- 
mates. In the case of Pogonomyrmex badius, this effect 
can be ascribed specifically to the mandibular gland secre- 
tion. 
The Release of Digging Behavior 
by the Mandibular Gland Secretion 
During the experiments described in the preceeding sec- 
tion, it was discovered that workers exposed several times 
in rapid succession to mandibular gland secretion fre- 
quently began to show digging behavior. The complex motor 
activity involved appeared to be identical in all respects 
to normal digging behavior observed during “nest work”, 
except that it tended to be undirected, i.e., unrelated to 
any oarticular topographic feature, and hence inconsequent- 
ial in results. Excavation started in this fashion further- 
more involved little interaction among workers, it ceased 
wh°n the exposure to the secretion ceased, and it was not 
followed up by later nest work- No attempt was made to 
determine the primary causation of the behavior. At least 
two explanations seem possible: (1) prolonged exposure 
to the secretion induced the behavior directly, (2) the 
behavior was a physiological by-product of a prolonged 
state of excitement caused by exposure. 
One is tempted to refer to the seemingly functionless 
digging behavior as a “displacement activity”, in the sense 
