Architecture in the Animal Kingdom. 103 



7m. respectively. Since the spring of 1897, however, 

 they had emigrated and I did not find them again. 

 In 1898 the northernmost of these nests was empty, 

 the central one was occupied by L. niger, and the 

 southernmost by Tetramorium caespitum. This was 

 the state of affairs until July, 1898. When I returned 

 on July 14, I found that the sanguineas of colony No. 

 y2, which I could easily recognize by the size of their 

 workers, had returned to the southern nest which con- 

 sisted of two little heaps in close proximity. From one 

 of these the Tetramorium had already been completely 

 driven out; in the other they still occupied a retired 

 corner and were surrounded by the sanguinea nest. 

 Therefore ant nests also have their fates. 



Ant nests are stolen not only by ants of different 

 species, but sometimes by those of different colonies 

 belonging to the same species. Many instances of this 

 kind are furnished by the sanguinea colonies in the 

 neighborhood of Exaten; but for brevity's sake, it 

 must suffice merely to mention the fact. 



3. The Nests of the Sanguine Slavemakers. 



The great plasticity and power of adaptation to 

 given circumstances in the nest-building instincts of 

 ants is seen to the greatest advantage by an examina- 

 tion of the nests of the sanguine slavemakers (F. san- 

 guinea). With members of one and the same species 

 possessing the same specific, natural constitution, there 

 is such a variety of nest construction, that there is no 

 trace of that "automatism" of instinct, which postu- 

 lates a completely uniform and monotonous manifes- 



