118 Chapter III. 



based the specific mode of building in any species of 

 ants. Why, therefore, introduce a foreign element, 

 called intelligence, between this hereditary disposition 

 and its changeable application? I should think it is 

 far more simple and natural to account for the whole 

 activity of an animal by one and the same principle. 

 Unless you mistake instinct for mechanical automa- 

 tism, it is by no means necessary to assume animal 

 intelligence in order to explain the above phenomena. 

 Let us now compare the architecture of ants with 

 that of birds. There are several important differences. 

 The nests of birds are more artistic 1 and regular; 

 yet they are stamped with the unmistakable marks of 

 monotony and uniformity within the same species, 

 they are products of instinct in the strictest sense of 

 the term. Moreover, as Altum 2 has admirably proved, 

 the architecture of birds is a function of their 

 breeding instinct. It begins at a certain stage 

 of the development of this instinct; both reach 

 their climax at the same time, and then grad- 

 ually vanish together. On this account the nests 

 for the first hatching in spring are, as a rule, built 

 better than those later in the season. In this case 

 practice does not form the master but the bungler. 3 

 With ants, however, architectural skill is found in the 

 workers throughout their life, it is suitably carried into 



*) By the way, this art has often been exaggerated. See "Die 

 Baukunst der Voegel auf ihren wahren Wert zurueckgefuehrt," in 

 "Jahrbuch der Naturwissensch." I (1885-1886), 198. 



2 ) "Der Vogel und sein- Leben" (6th ed.), p. 163 ff. 



3 ) Something similar obtains also among the Coleoptera in the 

 ingenious nest-building of the leaf -rolling beetle (Rhynchites betulae). 

 See Wasmann, "Der Trichterwickler, p. 78 ff. 



