THE PROGRESSIVE ODOR OF ANTS. 5 



T/ic JV2 group. During the first week in August, 1903, the 

 queen deposited about a hundred eggs, and from these were 

 reared five minor workers, denoted here as the N2 ants. These 

 workers hatched between April 24 and May 10, 1904, and were 

 therefore some fifteen months old at the time of the experiment 

 here recorded. These workers had never met other ants than 

 those of their own segregated group, and were therefore unac- 

 quainted with the odor of ants in any wise unlike themselves. 

 They had never lived with the queen, had laid no eggs, and had 

 the care of no young. On July 16, 1905, I put these ants into 

 a new and very small nest where I had isolated the queen-mother 

 without young. The five workers were wholly at ease with the 

 queen, and hastened to evince their devotion in ant fashion; but 

 the queen opened her jaws whenever they approached her, and 

 was somewhat querulous in her behavior during the ensuing two 

 days. The queen had lived during the previous five months with 

 daughters, all minor ants, less than five months old, and her be- 

 havior indicated a difference in the odor of her younger and her 

 older daughters. Her memory was manifestly less tenacious 

 than that of the workers, who, on their part recognized in their 

 queen the odor that had been their own in their infancy, fourteen 

 months earlier. 



The Nj group. This group consisted of two major workers 

 hatched in July, 1904, and four of their younger sisters, minor 

 workers, over five months and less than a year old, all the issue 

 of the N queen. The two majors were acquainted with sisters 

 older than themselves, while the minors knew no sister older 

 than these two majors. The members of this group had all lived 

 with the queen, and had been separated from her and living in 

 segregation since February 14, 1905. They had deposited no 

 eggs, and they had the care of a few introduced larvae. On July 

 1 8, 1905, I introduced into this group a sister nine months older 

 than the oldest in the group. The majors, who had had acquaint- 

 ance with sisters much older than themselves, did not attack the 

 newcomer at all, while every one of the minors, never having 

 met a sister so old as was the visitor, attacked, dragged and 

 finally killed her. 



It appeared that the behavior of the two major workers was 



