394 
Psyche 
[December 
Fig. 6c. The progress of recruitment and foraging activity at oak flakes 
widely dispersed. Details as in caption of fig. 6a. 
hadius attracts homing ants. His orientation experiments indicated 
that the Dufour’s gland secretion serves as a special chemical homing 
signal, since homing harvester ants closely follow artificial Dufour’s 
gland trails. These results raise the following question: Is the 
Dufour’s gland secretion used as an orientation cue for recruited 
ants as a supplement to the poison gland material? The following 
experiments were devised in an attempt to disentangle these two 
functions. 
An artificial poison gland trail was laid from the nest entrance 
over the bridge to the opening of the arena. In the arena the artificial 
poison gland trail was continued while an artificial trail made from 
the Dufour’s gland substance was simultaneously drawn at an angle 
of about 45 0 to the poison gland trail. In a second series the artificial 
poison gland trail was stopped at the arena entrance and then con- 
tinued in one direction with a Dufour’s gland trail and in another 
Poison Gland Dufour’s Gland 
Dufour’s Gland 
Hindgut 
N 
5 
5 
5 
5 
M ± sd 
70.8 ± 24.4 
20 ±10.4 
46 ± 11.3 
6 ± 3.5 
Range 
46-109 
9-36 
31-60 
2-10 
Table 3. In the arena a poison gland trail and a Dufour’s gland trail 
{left) or a Dufour’s gland trail and a hindgut trail {right) were offered 
simultaneously. During the next 5 minutes the ants which followed the 
trails were noted. The number of replications (N) as well as the mean 
and range of numbers of responding workers are given. The differences 
in response to the two trails are significant at the following levels: left, 
p < '0.005 ; right , p < 0.002. 
