RECOGNITION OF FRIENDS. 121 



The observation recorded by Huber was made 

 casually, and he did not take any steps to test it by 

 subsequent experiments. The fact, however, is of 

 so much importance that I determined to make 

 farther observations on the subject. In the first place, 

 I may repeat that I have satisfied myself by many 

 experiments, that ants from one community introduced 

 into another, — always be it understood of the same 

 species, — are attacked, and either driven out or killed. 

 It follows, therefore, that as within the nest the most 

 complete harmony prevails — indeed, I have never seen 

 a quarrel between sister ants — they must by some means 

 recognise one another. 



"Wlien we consider their immense numbers this is 

 sufficiently surprising ; but that they should recognise 

 one another, as stated by Huber, after a separation of 

 months, is still more astonishing. 



I determined therefore to repeat and extend hig 

 observations. 



Accordingly, on August 20, 1875, I divided a colony 

 of Myrmica ruginodis, so that one half were in one 

 nest. A, and the other half in another, B, and were 

 kept entirely apart. 



On October 3, I put into nest B a stranger and 

 an old companion from nest A. They were marked 

 with a spot of colour. One of them immediately 

 flew at the stranger ; of the friend they took no 

 notice. 



October 18. — At 10 a.m I put in a stranger and a 



