122 RECOGNITION OF FRIENDS 



friend from nest A. In the evening the former was 

 killed, the latter was quite at home. 



October 19. I put one in a small bottle with a 

 friend from nest A. They did not show any enmity. I 

 then put in a stranger ; and one of them immediately 

 began to fight with her. 



October 24. I again put into the nest a stranger 

 and a friend. The former was attacked, but not the 

 latter. The following day I found the former almost 

 dead, while the friend was all right. 



October 31. I again put a stranger and a friend into 

 the nest. The former was at once attacked ; in this 

 case the friend also was, for a moment, seized by the 

 leg, but at once released again. On the following 

 morning the stranger was dead, the friend was all 

 right. 



November 7. Again I put in a stranger and a friend. 

 The former was soon attacked and eventually driven 

 out ; of the latter they did not seem to me to take any 

 particular notice. I could see no signs of welcome, no 

 gathering round a returned friend ; but, on the other 

 hand, she was not attacked. 



Again, I separated one of my colonies of Formica 

 fusca into two halves on August 4, 1875, and kept 

 them entirely apart. From time to time I put speci- 

 mens from the one half back into the other. The de- 

 tails of this experiment will be found in the Appendix. 

 At first the friends were always amicably received, but 

 after some months' separation they were occasionally 



