THE PROGRESSIVE ODOR OF ANTS. 7 



their progressive odor. All the ants engaged in this last men- 

 tioned experiment were certainly the issue of the eggs laid by the 

 queen early in December, 1904. That there is similar progress 

 in odor among ants of the same age and species is indicated by 

 an immediate and amicable association of ants that are reunited 

 after a period of separation so long as two years. 1 



Whether two mutually hostile groups could be created from 

 among the worker-progeny of a single queen would depend on 

 power of memory in the older workers. By segregating from 

 the pupa-stage the broods of different summers, it would be 

 found that the younger sisters would always be hostile to the 

 older sisters, because the older sisters would present an unfamiliar 

 odor to the younger. The hostility of the older sisters toward 

 the younger would be nullified by their memory of the odors by 

 which they had themselves been characterized at earlier periods 

 in their own lives. If the younger sisters bore an odor which 

 the older sisters, through the lapse of many years, should have 

 forgotten, then the hostility would become mutual. It is certain 

 that worker-ants can remember for years an odor with which 

 they have once become familiar, and it is probable that they 

 remember such odors as long as they live. 



When ants of different groups meet amicably, either the mem- 

 bers of these groups have the same odor, or else they have at 

 some time in their lives been familiar with ants bearing the pre- 

 sented odor. If one group recognizes a familiar odor, while the 

 other group discerns a strange odor, then thos'e finding them- 

 selves among strangers will try to escape, or will make attack. 

 There is no love at first sight between ants of different odors. 



III. THE ODOR AND THE SENSE OF SMELL IN MALE ANTS. 



Male ants apparently bear a specific odor, beside the odor that 

 may be incurred during their residence with nurses in the home 

 nest. I have introduced males of different species into the nests 

 of Steitamma fu/vni/i, Cremastogaster lineolata, Mynnica ritbra, 

 Formica sanguinea, Formica Schaufnssi, Camponotus pennsyl- 



1 " A Cause of Feud Between Ants of the Same Species Living in Different Com- 

 munities," A. M. Fields, BIOLOGICAL BULLETIN, Vol. V. , No. 6, November, 1903, 



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