AFTER SEPAEATION FOR NEARLY TWO YEARS. 123 



attacked, as if some of the ants, perhaps the young ones, 

 did not recognise them. Still they were never killed, 

 or driven out of the nest, so that evidently when a 

 mistake was made, it was soon recognised. No one 

 who saw the diflferent manner in which these ants and 

 strangers were treated, could have the slightest doubt 

 that the former were recognised as friends and the 

 latter as enemies. The last three were put back on 

 ^Tay 14, 1877, that is to say, after a separation of a 

 year and nine months, and yet they were amicably re- 

 ceived, and evidently recognised as friends ! 



These observations were all made on Formica fusca^ 

 and it is of course possible that other species would 

 behave in a different manner. 



Indeed, in this respect Lasius flavus offers a sur- 

 prising contrast to F. fusca. I was anxious to see 

 whether the colonies of this species, which are very 

 numerous round my house, were in friendly relations 

 with one another. With this view, I kept a nest of L. 

 flavus for a day or two without food, and then gave 

 them some honey, to which they soon found their way 

 in numbers. I then put in the midst of them an ant 

 of the same species from a neighbouring nest ; the 

 others did not attack, but, on the contrary, cleaned her 

 — though, from the attention she excited and the 

 numerous communications which took place between 

 her and them, I am satisfied that they knew she was 

 Qot one of themselves. After a few minutes she accom- 

 panied some of the returning ants to the nest They 



