ANTS AXD ANT LIFE. 79 



no longer dig. They do indeed make attempts, but succeed 

 very badly. They then soil themselves and their larvae, 

 without being able to clean them, and at last give up wearied, 

 and remain only on the top of the nest. A great mistake 

 would, however, be made if it were thought that the scrap- 

 ing, digging, building, and wall-making of these little 

 creatures is, as the philosopher's instinct will have it, the 

 result of a tendency, changeless and compelling, placed in 

 the little mind of the ant. Jf this were the case it would be 

 impossible for some species of ants to seize as they do the 

 nests of others and establish themselves therein, although, 

 as Forel notices, the arrangements are often unsuitable for 

 them. They usually change the architecture a little, 

 especially outside, but as a rule the real builders can be very 

 quickly recognised if the nest be destroyed. An ant- 

 dwelling often changes its inhabitants in this way two, three, 

 four or more times, sometimes through voluntary and some- 

 times through forceful desertion. We shall see later that 

 there are also some species which do not build at all, but 

 leave building to their slaves. 



Still more against the instinct theory are the already 

 mentioned differences of building of the same species under 

 changes of circumstances. " Many nests or many parts of 

 nests," says Forel, " ai-e only provisional, while others are 

 intended to last for years ; many show very different styles 

 in their different parts. The plan of building also is very 

 much changed accordingly as the nest is meant for a larger or 

 a smaller community. The outside appearance of the nest 

 is also very different, accordingly as it is entirely closed with 

 the exception of one hidden entrance, or opens with many 

 holes on the outside (and this is true not only of different 

 species but also of the same), or the population is large or 

 small. The large thickly populated nests of F. fusca are 

 found opening on all sides, and the small nests of F. san- 

 guinea completely closed, while the contrary is the rule." 



"When danger threatens, for instance near a street, road, 

 or court, or when the surface of the earth is very hard, the 

 nests, mined or dug in the ground, betray their presence by 

 no sign, and can only be discovered by chance. The dug- 

 out earth is carried a long way off, and two or three con- 

 cealed holes suffice for inlet and outlet. Many of these 

 same ants at other places make a number of holes sur- 



