26 Chapter I. 



Sometimes one of the dominant, sometimes one of the 

 enslaved species is the recipient, no distinction being 

 made between masters and slaves in performing these 

 offices. Just as with cows in licking each other, so with 

 ants, the performance of this service generally causes 

 no less satisfaction to the active than to the passive 

 partner, and, when apes look for each other's parasites, 

 we must, in order to arrive at a correct psychological 

 appreciation of such "kind offices," not overlook the 

 fact that apes devour with great relish the parasites 

 discovered in the fur of their comrade. 



As regards these mutual cleaning services, ants 

 and the higher social animals are pretty much on a 

 par. The only difference is, that with ants they occur 

 much oftener than with the latter. In both they pro- 

 ceed, in the first place, from the desire for cleanliness, j 

 which is no doubt of an instinctive nature.^ In the ^^ 

 second place, they are due to the instinctive, mutual 

 attachment between the members of animal associa- 

 tions. The fact that ants clean a dust-covered com- 

 panion by carefully "brushing" her down with their 

 mandibles and licking her with their tongues, when 

 viewed from the point of comparative psychology, 

 finds its explanation in the same psychic motives as 

 when "apes, after having rushed through a thorny 

 brake, will examine each other's fur and extract every 

 thorn or burr." To lick off the dust is, by itself, not 

 more agreeable for ants; than it is for monkeys to 

 extract the thorns. 



With ants the mutual attachment of nest mates 



1) See Ballion, "De Tinstinct de la proprete chez les animaux," 

 2d ed., Bazas, 1895. 



