INTERNAL STRUCTURE. 



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the buccal tube, their separate ducts opening on a " cribellum " in 

 the lateral wall of the tube. 



The mandibular glands are large and consist of a number of cells 

 on either side of the head, their ducts opening separately on a 

 cribellum at the base of the mandibles. These glands supply the 

 cement which ants use in constructing carton, and plastering 

 particles of earth together, etc. 



The pharyngeal glands are finger-shaped and consist of two 

 groups, which extend in front of and over the brain, and open by 

 a pair of orifices into the alimentary canal. 



2. Thoracic Glands. 



The labial, or salivary glands, are situated in the thorax, though 

 they really belong to the mouth parts. They are large and paired, 



Vesicle 



Accessory gland 



Orifice of 

 accessory gland 



ting sheath 



Duct 



Vestigial 

 sting groove 



Fig. 34. Poison apparatus of Formica rufibarbis . (Forel.) 



and are connected by a single duct which opens on the labium. 

 They are derived from the spinning glands of the larva. 



The metathoracic glands consist of numerous cells, their ducts 

 opening through a sieve -like membrane into a chamber filled with 

 air. The orifice of this chamber and the cribellum, are sometimes 

 furnished with hairs. Janet has suggested that the secretion from 

 these glands gives to the ant's body the " nest-aura," by means 

 of which the ants in a colony recognize their fellows. 



The metatarsal glands are situated in the fore -legs, at the base of 

 the strigil. 



3. Abdominal Glands. 



The rectum is furnished with three rectal papillae, or glands, 

 the central one being situated on the dorsal, the outer pair on the 

 lateral surfaces. 



The glands belonging to the sixth abdominal segment (intra- 

 segmental " hautdriisen " Escherich) consist of small clusters of 



