14 Chapter I. 



tolerated cohabitants are found in the society of many 

 higher and lower animals. They are present like- 

 wise in the nests of social wasps, hornets and bumble- 

 bees; but genuine guests (Symphiles), which, in spite 

 of their morphological difference, are treated by their 

 hosts as enjoying equal rights, as members of the 

 family, are met with only among ants and termites. 

 That stray chamois or steinbocks should join a herd 

 of goats, is evidently something quite different from 

 the fact that ants keep aphides and scale-insects as 

 their milk cows, and tend even their eggs ; or that 

 they feed from their own mouths certain species of 

 beetles, which on being licked afford the ants a special 

 pleasurable sensation, herein treating them the same 

 as they do their own comrades and larvae. The 

 mutual social relationship which is here seen to exist 

 between the animals of different species, and which 

 we term Symphily (<rw-<i\x) is by far more per- 

 fect. Although, as we shall show later on, it is inti- 

 mately connected with the instinct of adoption which 

 occurs also among higher animals, the relation exist- 

 ing between ants on the one hand and their slaves 

 and genuine guests on the other, is nevertheless a 

 form of perfect Symbiosis unparalleled among the 

 Vertebrates. 



2. The Social Basis of Ant States. 



As was already indicated, the ultimate foundation 

 of ant states is organic. It is organic, not only be- 

 cause it is due to the descent from a common ovip- 

 arous female, but more especially because it is con- 

 ditioned, in its essential outlines, by polymorphism, 



