INTERNAL STRUCTURE. 



17 



INTERNAL STRUCTURE. 



The alimentary canal consists of a mouth opening and buccal 

 parts, an infra-buccal chamber, pharynx, oesophagus, crop, gizzard, 

 stomach, intestine, rectum and anus. 



The infra-buccal chamber is a spherical cavity situated below the 

 pharynx, and forms a receptacle for the solid and semi-solid parts 

 of the food rasped off by the ant's tongue, and also for foreign 

 matter scraped off the ant's body by its tongue and strigils. Any 

 juices that remain in these substances are extracted and sucked 



Crop 



Sepal 



Stomach 



Fig. 32. Gizzard of Formica pratensis $. (Forel.) 



into the pharynx, the residue being ejected in the form of a solid 

 body, the " Boulettes de nettoyage " of Janet, which retains the 

 shape of the infra-buccal chamber. 



The pharynx is situated in the head and is a flattened cavity 

 with very muscular walls which open and shut, forcing the liquid 

 food into the oesophagus. 



The oesophagus is a long tube connecting the pharynx with the 

 abdomen ; it is only feebly muscular. 



The crop is situated in the gaster, consisting simply of an en- 

 largement of the oesophagus. It forms a reservoir for the retention 

 of the liquid food, and is capable of great distension the " Honey- 

 Ants of the Garden of the Gods " represent the extreme form of 

 this phenomenon. Forel has called it the social stomach, as the 





