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[Vol. 91 
light. Since the gland is absent in a number of ant species known to 
be extremely aggressive and discriminatory towards conspecific 
foreigners and interspecific competitors (for Oecophvlla see Holl- 
dobler and Wilson 1978, Holldobler 1979, 1984; for Camponotus 
see Carlin and Holldobler 1983) it is obvious that at least in these 
species the metapleural gland secretions have no function in enemy 
identification. The absence of the metapleural gland in male ants is 
also much more widespread than previously assumed. In fact, it 
appears that species in which males lack this organ or possess it in a 
very reduced state outnumber those in which the gland is well 
developed. Most of these males never have to enter a foreign colony 
in order to mate. Thus Brown’s argument concerning the absence of 
the metapleural gland in doryline males is further weakened. 
In our view Maschwitz’s experimental evidence concerning the 
antiseptic effect of most metapleural gland secretions is very 
convincing. We have repeatedly heard the argument that the 
secretions of other pheromone glands, such as the mandibular gland 
or poison gland are also acidic and have the potential of suppressing 
the growth of Escherichia coli in test plates. Thus, it is argued that 
Maschwitz’s tests, although demonstrating an antiseptic effect, do 
not necessarily prove a primarily antiseptic function of the meta- 
pleural gland. Maschwitz himself has pointed out that other 
exocrine glandular secretions frequently have antiseptic power. In 
fact, he hypothesized that most epidermal glands originally were 
antiseptic devices before they became more complex glandular 
structures that produce either repellent secretions against predators 
or alarm pheromones used in social communication (Maschwitz 
1968, 1974; Maschwitz et al 1970). 
Metapleural gland secretions can freely flow out of the storage 
chamber. The meatus is sometimes densely covered with bristles 
(Fig. 6), and often there are hairs and dispenser bristles inside the 
atrium along which the secretion can easily flow to the outer surface 
(Fig. 6c). As Brown (1968) pointed out, “some ant species have been 
seen to draw the legs, especially the tibia and tarsi of the forelegs, 
repeatedly over the meatus of the gland and then rub these leg parts 
over the rest of the body”. In this way the metapleural gland 
secretion is probably spread over the whole body. It might also be 
distributed among nestmates by mutual grooming. Thus, it appears 
