AN'IS. 



brancs between the joints. Enough of the acid is absorbed by the vic- 

 tim's blood to cause temporary paralysis or even death. The Dolicho- 

 deriiue and some Myrmiciiue (Ischnomyrmex, c. g.) smear their victims 

 with a malodorous secretion from the anal glands, which seems to have 

 an equally irritating and noxious effect. While in many species some or 

 all of these aggressive measures may be adopted by the workers in 

 general, other species have a specially protective caste in the soldiers 

 (CaiiipDiiotns, Atta, Pheidole, etc.). In the subgenus Colobopsis the 

 soldiers guard the circular nest-entrance which they may even plug up 

 completely with their peculiarly modified heads (see p. 210). In Pol\- 

 cn/ns and Lcptogcnys all the workers have sickle-shaped mandibles 

 adapted to piercing the heads or bodies of their victims. 



Since many species of ants often live together in the same stations, 

 means have been developed for preventing the fusion or mixture of 

 colonies and the consequent exploitation of one species by another. 

 The general truth of this statement is not invalidated by the existence 

 of a small number of interesting species that have developed symbiotic 

 or parasitic instincts. As a rule, members of different colonies, even of 

 the same species, are so hostile to one another that they cannot meet in 

 numbers without a pitched battle. This hostility tends to restrict the 

 feeding grounds of certain species within very narrow limits. It is 

 -generally admitted that this segregation of colonies is clue to the pres- 

 ence of characteristic odors which vary with the species, colony and 

 caste, and, according to Miss Fielde, also with the developmental stages 

 of the individual. The specific odor may be readily detected even by the 

 blunted human olfactories. Thus the odor of Formica nifa is pungent and 

 ethereal, of Hypoclinea gagatcs and tnariff smoky, of Acanthomyops 

 like the lemon geranium or oil of citronella, of the species of Eciton 

 and some Pheidole, like mammalian excrement, of Crcuiastogaster lineo- 

 lata fainter but equally unpleasant, of Tapinonia like rotten cocoa-nuts, 

 etc. Undoubtedly ants are very quick to react to these various odors as 

 well as to the " nest-aura," or odor which every colony derives from 

 its immediate environment, brood, etc. For interesting accounts of 

 this important subject the reader is referred to the recent papers of 

 Bethe (1898) and Miss Fielde (1905^ to c}. 



While the protection of the colony centers in the activities of the 

 workers, the reproduction both of the individual ants and of the colony 

 as a whole centers in the males and females. The mating of the sexes 

 differs according to whether only one or both of the sexual forms 

 possess wings. No species are known in which both sexes are apte- 

 rous. In forms like Anergatcs, Symmyrmica, Fonnico.renus and some 

 species of Cardiocondyla and Poncra the male is wingless, whereas this 



