1970] 
Holldobler & Wilson — Recruitment Trails 
395 
Fig. 7. Above: Activity at the nest entrance before a poison gland trail 
was laid. Belov:: Immediately after a poison gland trail was laid from 
left to right. 
direction (45 0 ) with a hindgut trail. In both series all ants which 
entered the arena during the next five minutes and which followed 
one or the other of the two trails were counted. The results (Table 
3) indicate that the poison gland trail is much more attractive to 
recruited foragers than the Dufour’s gland trails. However, if the 
poison gland trail substance is discontinued and replaced by a Du- 
four’s gland trail, the recruited ants tend to follow the latter. 
Therefore it may well be that the Dufour’s gland secretion also 
serves as an additional orientation cue in recruitment trails. This 
problem draws additional interest from the fact, demonstrated by 
