ants' nests. 349 



friendly intercourse, while they are on hostile terms with all other 

 colonies of ants, even those of the same species. Certain kinds 

 of ants which live in trees form similar kingdoms by occupying 

 numerous trees of the same forest. 



In addition to this, ants frequently construct annexes to their 

 nests — covered ways, subterranean passages, stations, and flying 

 camps — in order to protect the plant lice which serve them as 

 milk cows, and also for other purposes. 



It is further to be remarked that there are courageous, warlike 

 kinds of ants, whose nests are, consequently, open and easily 

 discovered, while other kinds are timid and live in concealment, 

 in many cases, because their colonies consist of only a few 

 individuals. There are, besides, ants with good eyes, which 

 make their nests above ground, and even on the boughs of trees, 

 while there are blind and half blind kinds which live hidden 

 deep underground. 



As I have formerly asserted {Fourmis de la Suisse, 1874), the 

 chief feature of ant architecture, in contradistinction to that of the 

 bees and the wasps, is its irregularity and want of uniformity — 

 that is to say, its adaptability, or the capacity of making all the 

 surroundings and incidents subserve the purpose of attaining the 

 greatest possible economy of space and time and the greatest 

 possible comfort. For instance, the same species will live in the 

 Alps under stones which absorb the rays of the sun ; in a forest it 

 will live in warm, decayed trunks of trees ; in a rich meadow it 

 will live in high, conical mounds of earth. 



I will attempt to make a classification of the nests of ants, 

 corresponding approximately to that which I formerly made with 

 a view simply to giving an outline of the variety of the dwellings 

 of ants. Of course, taking into consideration the above-men- 

 tioned features of ant architecture, it is impossible to be 

 systematic. 



1. — Taking Advantage of Existing Cavities. 



Many ants use as nests simply the clefts and crevices of rocks 

 and the space between two stones. They wall up and barricade 

 the exterior of the clefts with sand, pebbles, and dry vegetable 

 particles ; they divide the surface, more or less, into chambers, and 



