CHAPTER XXI. 



PERSECUTED AND TOLERATED GUESTS. 



" Les Socieu^ de Eounnis sont rendues puissantes par le nonibre des indi- 

 vidus qui les composent, par la tenacite, le courage et les instincts compliques, 

 par les organes ires perfectionnes, les moyens d'attaque et de defense que 

 posse-dent ces individus; par le milieu favorable et la protection que leur fournis- 

 senl leurs retraites bien abritees ; par une division du travail qui pent etre 

 poussee ires loin. De toutes ces conditions particulierement avantageuses, il 

 resnlte que les Societes de Fourmis ont, en general, une existence extrememenl 

 longue et vivent dans une veritable opulence. II n'en faut pas plus pour ex- 

 pliqucr qu'un nombre aussi extraordinairement considerable d'especes animales 

 aient etc attirees pres d'elles, aient cherche a proiiter des avantages dont elles 

 jouissent, aient tente de vivre dans leurs nids, aient pu s'y installer a la suite 

 d'une accoutumance des Fourmis a leur presence et, dans certains cas oil ces 

 dernieres ont trouve tin avantage a cette presence, aient fini par etre soignees et 

 protegees par leur holes." Janet, " Rapports des Animaux Myrmecophiles avec 

 les Fourmis," 1897. 



The relations of the ants to the aphids and caterpillars described 

 in Chapter XIX represent only one of the many phases of symbiosis. 

 These relations, like those of the ants to the vascular plants, are of the 

 ants' own seeking and outside of their nests ; that is, they are extra- 

 nidal. The ants may even be said to be mildly parasitic on the aphids 

 and caterpillars. The symbiotic relations to be described in this and 

 the following chapter, on the contrary, obtain within the confines of 

 the nest and are therefore intranidal. In these relations, which are 

 extremely diversified, the ants are, as a rule, passive or indifferent, and 

 the other insects foist themselves upon the ants and assume the role of 

 satellites, parasites or commensals. Such insects, when they regularly 

 inhabit ant-nests, either throughout life or during one or more of their 

 developmental stages, are known as myrmecophiles, or ant-guests, in a 

 broad sense. The ants have such a plastic organization that they are 

 not only able to assume an active role towards the aphids and a passive 

 role towards the myrmecophiles, but. as will be shown in Chapters 

 XXIII to XXVII, they may even enter into manifold active and passive 

 symbiotic relations to other species of ants (social symbiosis). 



Our knowledge of the myrmecophiles is less than a century old. It 

 grew, slowly at first through the occasional contributions of J. P. \Y. 

 Muller ( 1818), Savi (1819), Maerkel (1841, 1844), von Hagens (1863. 

 1865), Lespes (18680, i868&), Forel (1874) and Lubbock ( 1894), but 

 recently the interest and importance of the subject have been more 



378 



