8 Chapter I. 



butterflies, dragon-flies and other insects have been 

 observed to form similar swarms. 



But few animal species are so perfect in their social 

 organization, that the members of the family construct 

 their habitations, rear their offspring and provide for 

 their food in common. These are what Aristotle calls 

 Zwo, 7roA.mKa, animals leading a well regulated social 

 life, comparable, in a way, to the social life of man. 

 These animals are chiefly the so-called state-forming 

 insects, the social wasps, bees, ants and termites. With 

 the two latter social life is carried to the highest degree 

 of perfection found in the whole animal kingdom. 

 True, also among birds, the social weavers (Ploceus) 

 construct habitations in common, inasmuch as they 

 build their nests close together, and beavers unite in 

 colonies to build their dams, when different pairs are 

 interested in raising the water level at the same spot. 

 But what is wanting in the associations of higher ani- 

 mals is co-operation, including some suitable division 

 of labor for the rearing and nourishing of their off- 

 spring. The combination of all these elements of 

 social life is found only among the social insects, and 

 in a prominent degree among ants. 



Viewed from the standpoint of comparative psy- 

 chology, social is preferable by far to single life. In this 

 connection, of course, we mean a social life based on 

 social instincts, on the laws of sensitive cognition, and 

 not merely a union caused by the laws of vegetative 

 life, as is the case with certain animal conglomerates, 

 as sponges, corals, polyps and many species of Tuni- 

 cates. The bond, which unites the different individuals 

 of these species to a colony, is entirely material. They 



