THE PROGRESSIVE ODOR OF ANTS. I 5 



deaths, such as sometimes occur in nests where amity has long 

 prevailed, are probably to be explained by the attainment by some 

 of the inmates of a new and therefore an alarming progressive 

 odor. 



There may be seen among ants of the same variety, and even 

 in the same individual, all degrees of attraction and repulsion 

 towards other ants at a first meeting with them. Such manifes- 

 tations range all the way from cuddling, caressing, cherishing de- 

 votion through indifference and inattention, distrust, suspicion, 

 animosity and enduring, ferocious enmity. The inciting cause 

 is doubtless the progressive odor of the visitor, and the prac- 

 tical end is the preservation of the chemical standard of the nest. 



Whatever the action of the ants, it is always more obvious 

 when there are numerous young in the nests, and when the nest- 

 aura is well established. 



During five years of fairly constant study of ants I have seen 

 no evidence that their antennae are the organs of any other sense 

 than the chemical sense, and I am convinced that any statement 

 concerning the behavior of ants may well be distrusted if it ignore 

 the dominance of the olfactory sense over the conduct of the ant, 

 the ant's almost inconceivable minuteness of discrimination in 

 odors, or the ant's marvelous memory of odors that have been 

 encountered. Only when ants are segregated from the pupa- 

 stage, and full record kept of every experience of theirs in meet- 

 ing other ants, can the investigator truthfully declare that ants 

 behave in a certain manner in the presence of other ants. More- 

 over, as every ant acts on personal experience and individual 

 memory, the ants should be considered singly as well as in 

 groups and communities, when a theory of their behavior is to be 

 enunciated. But when the total history of an ant is known, the 

 investigator may accurately predict the behavior of that ant 

 toward other ants. There is ex-ceeding uniformity of behavior 

 among ants having an identical history. 



The progressive odor of the worker ants is manifestly an ad- 

 vantage in their communal life, since it furnishes the means 

 whereby every ant can recognize its home and its fellow-citizens, 

 avoiding nests and communities other than its own. The uses of 

 this odor within the colony may also be numerous, and it may 

 determine the distribution of labor in the ant community. 



