540 PROCEEDINGS OF THE ACADEMY OF fOct., 



an odor which is a component of the aura, she may be eventually 

 accepted as an associate. If, in a group of ants reared in equal 

 numbers from the pupa? of two colonic?, C and E, I introduce an 

 ant, deprived of smell-sense, from either the C or the E colony, 

 the fearless newcomer is received with excitement and alarm and 

 may be attacked with violence. But the attack is never fatal, 

 and the blood-relative of half the group is eventually permitted to 

 remain peacefully in the nest. ^Yheu a whole ant from either C 

 or E colony is introduced, the newcomer manifestly discerns an 

 unfamiliar aura and either flees or else fights to a fatal end. 



The sensitivity of the normal ant to the aura of an alien nest 

 causes her to flee from it when escape is possible, and to endeavor to 

 hide hei'self when she cannot escape. I have deprived many ants 

 of the distal segments of the antennae, and have found that on 

 complete recovery from shock-effect their behavior was to be dis- 

 tinguished from that of normal ants by the absence of an exhibition 

 of alarm when introduced into the nest of aliens. Such maimed 

 ants do not flee, nor do they endeavor to hide, nor do they hesitate 

 in close approach to a dense swarm of aliens. Their conduct when 

 introduced into the nests of other colonies is strikingly different 

 from that of the whole ant. Their action, whether in their own or 

 an alien nest, evinces unconsciousness of the aura that determines 

 the advance or retreat of the whole ant, or causes it, with uplifted 

 and waving anteunte, to pursue an object that is beyond its reach. 

 Callows reared from the third day of the pupa-stage with no asso- 

 ciation with other ants until the tenth day of active life, had then 

 established their owa aura, without the presence of a queen, and 

 manifested alarm at the introduction of aliens. 



If the subtile aura of the nest, imperceptible as it is to human 

 nostrils, is diffused by a vibration in the body of the living ant 

 which it envelops, the aura should be strongest where the greatest 

 number of ants have lougest lived. Its allurement in the air 

 or ether may be what sometimes causes an ant to return to an old 

 and empty habitation, and to carry back pupai that have already 

 beeii transported to a newly occupied nest. 



The excitement occasioned by the intrusion of an alien among 

 ants that are a few millimeters from the point at which the alien 

 passes, indicates that the aura borne by the introduced ant extends 

 at least a few millimeters from its body. The behavior of the 



