80 ANTS AND ANT LIFE. 



rounded by the thrown up earth, the so-called " craters," 

 and thereby keep up communication with the outer world. 

 The earth between these craters is often so heaped up 

 that the whole has the appearance of a walled dome, 

 although nothing of the sort is intended. The ants which 

 generally build walled nests know how to make mined or 

 dug nests according to circumstances, and the reverse is 

 also the case. Timid species ^such as Myrmecina Latreillei) 

 make the passages in their dwellings so narrow that two can 

 scarcely pass each other, so as to protect themselves against 

 the incursions of hostile ants, while F.fusca seeks to guard 

 itself from the marauding excursions of slave-making 

 species by placing the outlet from its nest as far off as pos- 

 sible, and uniting it to the nest by a long and very winding 

 path. It is just the same with these nests as with the human 

 robber-caverns or knightly castles of the middle ages, 

 which had just such hidden ways of escape. Within the 

 nest two different sorts of passages are often found, whereof 

 the larger and more regular is for the use of all sexes, while 

 the slighter and narrow one, which is often hard tq find, is 

 for the workers only. 



In nests built under flat stones it is above all important 

 to prevent the stone, after it is undermined, from sinking 

 and injuring the nest. In order to attain this object, the 

 ants make thick pillars and walls of earth between the 

 rooms and galleries, and the heavier the stone the thicker 

 its supports. For the rest, they choose their stone carefully, 

 which must be neither too large nor too small, neither too 

 thick nor too thin more especially the last, so that it may 

 not heat nor cool too rapidly. The nest is partly dug out, 

 partly built. Of these are generally the so-called " double 

 nests," which consist of nests built and inhabited by two or three 

 quite different species. These live beside each other peace- 

 fully, because their dwellings are separated from each other 

 by strong partition walls, which pass through the whole 

 thickness of the nest from above to below. If the stone 

 be lifted, the enmity or dislike breaks out, and nothing is 

 more comic than to see the haste wherewith each kind 

 seeks to save its own young in the lower rooms. 



The most elegant dwellings, although constructed essen- 

 tially in the same way as those already described, are those 

 made by many species in wood, especially in old tree 



