POWER OF RECOGNITION AMONG ANTS. 



241 



when engaged in the care of their own young, they have, unless 

 previously acquainted with Cremastogasters, always killed the 

 Cremastogasters as soon as the latter hatched and began to move 

 about. It appears that the Stenammas of nest Bi recognized an 

 old acquaintance in the young Cremastogasters of the H colony, 

 and resumed toward them their accustomed behavior. In other 

 words the Stcnaiiunas recognized an odor after an interval of ten 

 months in ivhich that odor Jiad not been encountered. 





FIG. 4. Cremastogaster litieolata ; magnified. Actual length 5 millimeters. 



Having removed all Cremastogasters from nest Bi on August 

 4, there followed an interval of twelve days in which they had met 

 no Cremastogasters. Then on August 16, 1904, I introduced to 

 their nest one of their old comrades in nest B, a Cremastogaster 

 from whom they were separated on September 24, 1903. This 

 visitor was killed by them within a few hours. In less than 

 eleven months she had attained an odor unknown to them. 



Nest B2. - -There were in April, 1904, so few of the Lasius 

 in this nest that I gave their power of recognition no test within 

 their own nest. All of them were used till their extermination, 

 in the experiments in nests Bi and 63. 



