38 PROCEEDINGS OF THE ACADEMY OF [Jan., 



(5) The next two segments, the sixth and seventh from the proxi- 

 mal end of the antenna, discern the odor of ants of alien species, 

 always regarded and treated as enemies unless acquaintance has 

 been made in the earliest days of the individual ant's existence. 

 Prolonged warfare and terrible slaughter often occur between ant 

 colonies of different species. But if the sixth and seventh segments 

 of the antennae be eliminated, ants of different species or even of 

 different sub-families will live together amicably and will regurgitate 

 food to one another. I have had representatives of so mam- as 

 five different genera living in close fellowship in the same nest. 

 The specific odor is discerned by contact, the antenna being applied 

 to some part of the body of the ant encountered. (See h, page 321; 

 k, page 229.) 



The two antennae of the ant are identical in function, either one 

 serving the purposes of both. Among the three or four thousand 

 species of known ants the number of segments in the antennae varies 

 from four to thirteen. In my work of ascertaining the function of 

 the antennal segments, I used mainly Stenamma fulvum piceiim, a 

 Myrmicine ant, having twelve segments in the antennae. It is not 

 improbable that further investigation, equally painstaking, would 

 reveal olfactory functions in other segments than those tested by 

 me. It is certain, however, that segments proximal to the sixth 

 do not discern the odors appreciated by the seven at the distal end. 



Since the ants have given evidence that they bear in their bodies 

 several different odors, they must have glands producing unlike 

 odors. The nest aura requires no separate apparatus, because its 

 creation is effected by the combined odors of the inhabitants of the 

 nest. The colony odor, inherited from the queen and changing with 

 age of the ants, demands a means of production that might well be 

 inquired for along the sides of the thorax where the ants so commonly 

 apply a caressing antenna. The scent that is laid down on the 

 track would probably issue from the feet or legs, while the odor of 

 the queen would be produced in some gland that would be no more 

 than rudimentary in the workers. The diverse specific odors are 

 easily discernible by human nostrils; and even an ant may be tem- 

 porarily deceived by an individual of the enemy's troop painted 

 with the blood of a friend. There must be glands for producing 

 this odor. • 



Many observers have described certain vesicles in the integument 

 of ants, as well as of many other insects, since Hicks first studied 

 them. (1857 to 1860.) Janet, whose work on the anatomy of the 



