46 
Psyche 
LJune-Septembek 
fully from the nest, anesthetized, and dissected, the gland 
reservoirs have been partly or completely filled with a 
colorless fluid. When the reservoir walls are ruptured 
this fluid evaporates within several seconds and the char- 
acteristic pungent odor can be perceived by the human 
observer over a distance of 50 centimeters or more. 
The releaser effect of the mandibular gland secretion 
was demonstrated in the following way. When workers were 
seized with forceps and held about two centimeters above 
groups of resting workers just outside the nest entrance, 
alarm behavior was induced in the resting workers after 
an interval of several seconds. The captive workers were 
not stridulating, thus eliminating the possible complication 
of this additional stimulus, but they were releasing suffi- 
cient quantities of mandibular gland secretion to be dis- 
cernible to a human observer a short distance away- 
Freshly killed workers, which were not producing dis- 
cernible amounts of the secretion, elicited no response 
when held above resting workers. 
When workers were crushed between two pieces of glass 
above groups of resting workers, large quantities of the 
mandibular gland secretion were released, and high-intens- 
ity alarm behavior was elicited. That the effect was in fact 
proluced by the mandibular gland substance and not by 
other substances released by crushing was tested in the 
following experiment. In separate trials various parts of 
an anesthetized worker were isolated and crushed above 
groups of workers in the manner described. Each body 
part was tested from a total of ten workers. The sequence 
of presentation was randomized to eliminate possible spe- 
cial sequential effects. Also, the trials were spread over 
a period of several days to reduce the decline of response 
due to adaptation. The results, presented in Table 1. 
show that the relatively minute mandibular gland produces 
more effect than any other part of the body, no matter 
how large. No attempt has been made to determine the 
extreme distance over which the contents of a single gland 
can act; the experiments described here suggest that it 
it not less than five centimeters at room temperature 
( 26 ° C). 
