1908] The Polymorphism of Ants 47 



(20) The dinergate, or soldier, is characterized by a huge head 

 and mandibles, often adapted to particular functions (fighting 

 and guarding the nest, crushing seeds or hard parts of insects), 

 and a thoracic structure sometimes approaching that of the fe- 

 male in size or in the development of its sclerites (Pheidole). 



(21) The desmergate is a form intermediate between the typi- 

 cal worker and dinergate, such as we find in more or less isolated 

 genera of all the subfamilies except the Ponerinas, e. g., in Cam- 

 ponotus, some species of Pheidole, Solenopsis, Pogonomyr- 

 mex, Azteca, Dorylus, Eciton, etc. The term may also be em- 

 ployed to designate the intermediate forms between the small and 

 large workers in such genera as Monomorium, Formica, etc. 



(22) The plerergate, "replete", or "rotund," is a worker 

 which in its callow stage has acquired the peculiar habit of dis- 

 tending the gaster with stored liquid food ("honey") till it be- 

 comes a large spherical sac and locomotion is rendered difficult or 

 even impossible. This occurs in the honey ants (some North 

 American species of Myrmecocystus, some Australian Melophorus 

 and Camponotus, and in a less extreme form in certain species of 

 Prenolepis and Plagiolepis) . 



(23) The pterergate is a worker or soldier with vestiges of wings 

 on a thorax of the typical ergate or dinergate form, such as occurs 

 in certain species of Myrmica and Cryptocerus. 



(24) The mermithergate is an enlarged worker, produced by 

 Mermis parasitism and often presenting dinergate characters in 

 the thorax and minute ocelli in the head. 



(25) The phthisergate, which corresponds to the phthisogyne 

 and phthisaner, is a pupal worker which in its late larval or semi- 

 pupal stage has been attacked and partially exhausted of its 

 juices by an Orasema larva. It is characterized by extreme sten- 

 onoty, macrocephaly and microphthalmy, and is unable to pass 

 on to the imaginal stage. It is in reality an infra-ergatoid form. 



(26) The gynandromorph is an anomalous individual in which 

 male and female characters are combined in a blended or more 

 often in a mosaic manner. 



(27) The ergatandromorph is an anomaly similar to the last 

 but having worker instead of female characters combined with 

 those of the male. (Wheeler, 1903.) 



It is usually stated that the fertilization or non-fertilization of 

 the egg of the social Hymenopteron determines w^hether it shall 

 give rise to a male or female. And as the queen represents the 



