Contents. 



PAGE. 



2. The war-like expeditions of the Amazon ant and the 



Formica sanguinea 44 



Their tactics, the "humanity" of the victors. The military 

 skill of the Amazon ants; their inability to feed themselves. 

 The military tactics of the sanguine slavemaker {Formica 

 sanguinea) discussed on psychological grounds. 



3. The pretended "automatism" in the psychic life of ants 55 



The individuals of one and the same colony act differently 

 in combat. Acquired individual habits. Persecution of toler- 

 ated or even of true guests. Ants tamable. Psychic influence 

 of the numbers of a colony on their courage in combat. 

 Marked "heroism" of individuals. Martial sports? 



4. The slave-making instincts of Formica sanguinea 6y 



"Tradition and instruction" in insect communities. Experi- 

 ments made with "self-taught" ants and bees. Seemingly 

 intelligent plasticity of the instinct of slavery in Formica 

 sanguinea, both with regard to the number and to the species 

 of its slaves. On the nature of slavery in ants. The correct 

 explanation is neither anthropomorphism nor mechanic automa- 

 tism, but something between the two. 



5. Other wars and alliances of ants 82 



Fights between neighboring colonies. Alliances between 

 hostile colonies, and their psychological explanation. Summary. 



CHAPTER III. 



ARCHITECTURE IN THE ANIMAL KINGDOM. 



1. A general survey of the architecture of animals 90 



2. The nests of ants 93 



Various and arbitrary forms of their nests. Nests of dif- 

 ferent ant species. Psychological explanation of this difference. 



3. The nests of Formica sanguinea 103 



Variety and plasticity in their forms. Variable number of 

 the nests of a colony. Periodic changes of nests; different 

 places of residence in different seasons. These phenomena 

 psychologically explained. Power of adapting the construc- 

 tion of their nests to the surroundings, in order to secure 

 them against hostile inroads. 



4. How do ants build their nests ? I14 



No rigid system of co-operation; seemingly intelligent self- 

 determination. Suitable consideration of the different con- 

 ditions of temperature and moisture. Architecture of birds 

 compared with that of ants; with that of mammals, in par- 

 ticular of beavers. 



ix 



