86 Chapter II. 



ants reason thus : "Why this useless shedding of 

 blood ? Let us not exterminate each other but live in 

 peace; our differences are not so great that we can- 

 not come to terms!" Yet, there is not a shadow of 

 proof that ants entering into an alliance reason in this 

 manner. The phenomenon, which is indeed singular 

 enough, can be explained more simply and naturally 

 from the laws of instinctive sensation, with special 

 regard to the feeler sensations. Especially with the 

 Formica species, and among these, most of all with 

 the highly endowed F. sangiiinea, the hereditary dis- 

 position of the sensitive powers of cognition and appe- 

 tite is so plastic, that with parties of almost equal 

 numbers fear will be stronger in such cases than 

 love of combat. First, of course, by tapping one 

 another with their feelers they find out that they are 

 strangers, and therefore they try to avoid each other ; 

 but if this is impossible, the perception of mutual 

 similarity will gradually prevail over their mutual dif- 

 ference. In the beginning, they live together from 

 necessity only, but they gradually acquire a common 

 nest-smell which unites them as members of one 

 colony. From this time, by taps of their feelers, they 

 recognize one another as belonging to the same house- 

 hold. The former opponents have united into one 

 "constitutional body" which is kept together by the 

 common nest-smell. Strange though this mode of 

 communication may appear to us who are not pro- 

 vided with antennae, it alone explains the fact other- 

 wise wholly inexplicable, how the confederate colony 

 thus formed will in future hold together even against 

 former members of their own colony.^ An example 



1) On the explanation of the nest-smell see above p. 16 ff. 



