40 BRITISH ANTS. 



wingless, and possessing a more simply constructed thorax. The 

 ocelli, which when present are smaller than in the female, are often 

 wanting ; the eyes and gaster are small, and the mandibles, antennae 

 and legs are well developed. The largest and smallest workers, in 

 many species, are connected by a series of intermediate forms. 

 With species in which the worker is dimorphic, the intermediate 

 forms have disappeared, and further where only a very small 

 worker is always present, the large worker has also been eliminated. 

 20. The pterergate is a worker with vestiges of wings, the thorax 

 being either that of the normal worker, or somewhat approaching 

 that of the female. 



Fig. 49. Pseud ogyne of Formica riifa var. rufo-pratensis fastened 

 to the leg of a worker. Nethy Bridge, V. 1912 This proves 

 pseudogynes will fight and bite. (Bondroit.) 



21. The mermithergate is a somewhat enlarged worker, due to 

 the presence of an internal worm of the genus Mermis. The pres- 

 ence of the parasite in the worker appears to produce excess, instead 

 of defective characters as in the male and female. Thus small 

 ocelli and a tendency towards the female thorax may result 

 from it. This phase has not been discovered in any British 

 worker-ant. 



22. The plerergate, replete, or rotund, is a worker which in its 

 callow stage has acquired the habit of distending the gaster with 

 liquid food. The well-known " honey ants " are the best examples, 

 and no such form occurs in Britain. 



23. The macrergate is larger in stature than the normal worker 

 of the species in question, and is usually present in populous 

 colonies, 



