3^ ANTS. 



>een, is bounded above by the labrum and ciypeus, on tbe sides by the 

 maxillae, and below by the protrnsible tongue, leads into a short, com- 

 pressed buccal tube, dilated ventrally to form a spheroidal sac, the infra- 

 buccal cavity or chamber (lip). This chamber is of great importance 

 to the ant as a receptacle both for the fine particles of solid and semi- 

 solid food rasped off or licked up by the tongue, and for the foreign 

 matter scraped from the surfaces of the body by this organ and the 

 strigils. Any juices that may be contained in the substance are sucked 



back through the pharynx into the crop and the 

 useless solid residuum is eventually thrown out 

 as a little body which preserves the form of the 

 chamber in which it was moulded. Such bodies, 

 called by Janet " corpuscles de nettoyage," are 

 often seen scattered about the floors of artificial 

 nests after the ants have been fed on starchy 

 substances or after their bodies have been dusted 

 with plaster of paris (Fig. 14). The short 

 FIG. 14. Pellets or buccal cavity is continued back into the muscular 



castings from the in- . . .,, r , - 



frabuccal chamber of pharynx which narrows still further to form the 

 Formica mfa, enlarged. i on g oesophagus traversing as a slender tube the 



head, thorax and pedicel (Fig. 13, oe). 



The buccal tube, which, according to Janet, " has a protractor and a 

 retractor muscle, is provided \vith soft lips that can be applied to the 

 surface of the substances previously rasped off by means of the tongue 

 for the purpose of obtaining any liquid they may contain. Transverse 

 scale-like folds with their points turned outward line the walls of the 

 buccal tube and serve to retain any solid particles not sufficiently 

 minute." 



' The pharynx is a flattened cavity the dorsal and ventral walls of 

 which are moved by powerful dilator muscles. Behind it is furnished 

 with two expansions arising laterally and united at their tips by a 

 transverse constrictor muscle. During aspiration the pharynx, through 

 the action of its dilators and a kind of posterior sphincter, opens in 

 front and closes behind. In swallowing there is first produced a steel- 

 yard-like movement of the dorsal wall, whereupon the pharynx is 

 opened behind, while the buccal tube is closed in front. Then, owing 

 to the action of the transverse constrictor, the dorsal approaches the 

 ventral wall from before backward. The two walls thus come in con- 

 tact with each other and the liquid which was contained in the pharynx 

 is pushed into the oesophagus." Immediately behind the pharynx two 

 groups of finger-shaped post-pharyngeal glands open by a pair of 

 orifices into the alimentary tract ( F\g. 13, 



