ANTS. 



can easily be seen how such a strong odor might be developed through 

 the action of natural selection, from the small trace of leucine that is 

 usually present in insect feces." As I have found a secretion precisely 

 like that of Eciton in certain carnivorous Phcidolc (Ph. ccitonodora 

 and anfillcnsis ), J infer that its chemical constitution may, perhaps, 

 depend on the diet of the insects. 



In all ants, both in those with the pulvinate and those with, the buur- 

 releted glands, there is present a so-called accessory, or Du four's gland 

 ( Fig. 20, //, Fig. 21, d), which opens into the duct of the poison vesicle 

 very near its termination. This gland is ventral to the poison apparatus 

 and though of variable form (pyriform, cylindrical or bilobed ) is 

 rather uniform in structure throughout the family Formicidae. It is a 

 small, elongated sac, with rather thin walls composed of polygonal 

 gland cells enveloped by delicate muscles and tracheae. Several authors 

 have regarded its rather thick, yellowish secretion as a lubricant for 

 the parts of the sting, but Janet has shown that no such lubricant is 



necessary. Moreover, the 

 gland is often best devel- 

 oped in virtually stingless 

 ants like the Camponotinse. 

 Others have surmised that 

 the secretion is added as a 

 necessary ingredient to the 

 poison. Janet finds that it 

 is alkaline and conjectures 

 that its chief use is to neu- 

 tralize any of the highly 

 acid poison which may 

 happen to adhere to the 

 ant's own body or remain 

 on the parts of the sting 

 or on the anal circlet after 

 the gland has been dis- 

 charged. He also finds 

 that all the other integu- 

 mentary glands, except 

 those of the poison appa- 

 ratus, have an alkaline re- 

 action, and believes that 

 this is important in pre- 

 venting the nest chambers from becoming acid, for the secretions of 

 the poison glands, if allowed to accumulate in a closed cavity, soon 



-t 



FIG. 22. Repugnatorial glands and vesicles 

 of worker Bothriomyrmex ineridionalis. (Forel. ) 

 A, Whole structure seen from above; a, vesicles; 

 o, common orifice of same ; g, clusters of unicel- 

 lular glands; d, duct; i, intima ; m, muscles in 

 wall of vesicle. B, Single gland cell (c) contain- 

 ing the convoluted termination of the ductlet (e) 

 in its cytoplasm ; d, main duct ; /, trachea. 



