Architecture in the Animal Kingdom. 115 



In building nests the single workers co-operate 

 differently in different species ; nowhere, however, do 

 they co-operate with the regularity of a machine or 

 according to a rigid pattern, but each ant with evident 

 liberty follows her own impulse and her own plan. It 

 is above all the instinct of imitation, which neverthe- 

 less causes a uniform result, a nest consisting of com- 

 municating galleries and chambers. As a rule the 

 most zealous and skillful worker is imitated most; 

 her zeal is catching, so that she directs the activity of 

 the others into the same channel. This mode of 

 co-operation effected 'by means of the instinct of imi- 

 tation is predominant in hill ants (F. rufa) and the 

 small, blackish garden ants (Lasius niger) . F. fusca, 

 however, the greyish-black slave ant or negro ant, 

 (Huber's fourmi noir-cendree) belongs to those 

 species, in which the independence of the several 

 workers in building is especially remarkable. The 

 same is observed with the closely allied F. rufibarbis 

 (Huber's fourmi mineuse). I often witnessed in 

 these two species, how the pellets of earth, which one 

 worker had just put down for building a wall in a 

 certain place, were carried away by another one in 

 order to apply them elsewhere in a manner more suit- 

 able to her own taste. To observers, who know the 

 habits and doings of ants but superficially, and are 

 wont to transfer their own thoughts into the brain of 

 the animal, such occurrences may appear as though 

 an ant wished "purposely to correct" the work of 

 others. And, as a matter of fact, one of P. Huber's 

 observations 1 bearing on this head has been actually 



!) L. c., p. 43. 



