CHAPTER XXVII. 



THE DEGENERATE SLAVE-MAKERS AND PERMANENT SOCIAL 



PARASITES. 



" Concluons done que le parasitisme n'est inoffensif qu'accidentellement et 

 que son effct normal est de nuire. II faut par consequent considerer comme 

 aussi eloigne que possible de 1'imion sociale tout etre qui se nourrit de la sub- 

 stance d'un autre. Au point de vue physiologique sa fonction est en opposition 

 avec celles de sa victime ; au point de vue psychologique il n'entre dans la 

 sphere de sa conscience que pour y causer de la douleur, autre signe non moins 

 manifeste d'opposition. II appartient a un optimisme pins courageux que clair- 

 voyant de chercher une harmonic an sein de la plus apre concurrence. Mais le 

 parasitisme ne unit pas settlement a la victime, il unit au parasite lui-meme, 

 sinon immediatement dans 1'individu, du moins par accumulation dans 1'espece." 

 Espinas, " Des Societes Animales," 1877. 



The true slave-making ants, both facultative and obligatory, are 

 closely allied members of the Camponotine subfamily. The ants to be 

 considered in the present chapter, however, are all Myrmicinae and 

 cannot, therefore, have arisen from such forms as sanguined and Poly- 

 crgiis. Considered by themselves they represent a heterogeneous assem- 

 blage of remotely related genera, which may be described in the order 

 of increasing degeneration. Several of these ants resemble their respec- 

 tive hosts so closely that it is from these that some authors suppose 

 them to have been derived. But this supposition, though plausible, is, 

 nevertheless, open to doubt, for the resemblance between host and 

 parasite may be due to mimicry and therefore to convergence rather 

 than to true morphological relationship. We have seen that many 

 myrmecophiles, some of the temporary parasites, like Formica conso- 

 cians, and some of the amazons simulate their hosts, and it is con- 

 ceivable that parasites as extreme as those we are about to consider, 

 might show even more striking resemblances as the result of a long 

 process of adaptation and association. Very similar resemblances are 

 also known to obtain between many parasitic bees of various genera 

 and their respective hosts. 



The symbiotic ants with which we are here concerned, fall naturally 

 into two groups. Those which I shall call the degenerate slave- 

 makers, resemble Polyergus in certain respects, but differ in permitting 

 the queens of the host species to survive and reproduce in the mixed 

 colonies. The permanent social parasites, on the contrary, live in host 

 colonies whose queens have been eliminated, and differ, moreover, from 



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