1904.] NATURAL SCIENCES OF PHILADELPHIA. ' 641 



inherent odor became subject to the critical examination of an associate 

 or of the queen. Then instinctive race-prejudice impelled the Cremas- 

 togasters to eliminate from their community one whose education had 

 already been such as to secure them from injury through her misbe- 

 havior. 



3. Can an ant remember acquaintances after lapse of three j^cars or 

 more? 



In August, 1904, I had a nest of Camponotus pennsylvanicus , con- 

 taining some larvoe and fourteen large workers, all of whom had hatched 

 in my nests between l\Iay 1 and May 10, and who were therefore about 

 three months old. They had spent the first two months of their lives 

 with Stenamma fiilvum ants who were from seven to nine months old, 

 and they had not met ants of other species. They had been segregated 

 about one month, when I dropped into their nest two Formica lasiodes 

 of unknown age. several newly hatched Stenamma fulvum of the C 

 colony, two adult Stenamma fulviim of the X colony and two Stenam- 

 ma fulviim that were more than three years old, having been captured 

 as adults and kept three years in one of my artificial nests, a section of 

 the C colony. From the first introduction of these ants to the nest 

 of Camponotus, one of the three-year-old Stenammas, who was of the 

 same colony as were the early acquaintances of Camponotus, went 

 freely and happily among them, apparently without fear and without 

 reproach. She was permitted to stand among or upon the cherished 

 larvce, or on the backs of the resident ants. The affiliation between 

 her and them was as complete as if she had always lived among them. 

 Her odor may have become familiar to them in the nest of Stenammas 

 where they had spent their early lives. But if this Stenamma had ever 

 been acquainted with Camponotus it was at a time previous to her resi- 

 dence in my artificial nests, and more than three years since she had 

 met any ant of other species than her own. The remarkable ease and 

 friendliness of her intercourse with these ants, among whom she was as 

 a brown pigmy among black bristly giants, is a fact requiring explana- 

 tion; and the only explanation offered by known characteristics of ants 

 lies in her recognition of an odor that she had previously encountered, 

 and that she recognized the odor after the lapse of more than three 

 years. 



All the other ants introduced at the same time as was this Stenamma 

 were killed by the resident Camponotus within a few hours. The 

 Stenamma continued to live among the Camponotus until I removed 

 her at the end of eight days. 



The incidents were observed at the ^larine Biological Laboratory 

 at Wood's Hob, Massachusetts. 



