Architecture in the Animal Kingdom. 101 



Within the limits of these instinctive, hereditary dis- 

 positions there is plenty of room for the worker ants 

 to give full play to their individual powers of sensitive 

 cognition and appetite. This is why certain ant spe- 

 cies, particularly those skilled in earth work or wood 

 work, often take possession of some spot so suitable 

 for their dwelling as to be practically half-finished. 

 This they fit up in a becoming manner as a home for 

 their colony. Such attractive spots are e. g. on the 

 heaths of northern Europe rotten tree-stumps, in which 

 for years numbers of bark-beetles and their larvae or 

 other wood-boring insects were kind enough to prepare 

 comfortable quarters by carving out an extensive sys- 

 tem of galleries and chambers. It only remains for 

 the ants to take possession of the lodgings, devour 

 the former inhabitants, if there be any left, clean the 

 apartments, close up the superfluous entrances with 

 earth or rotten wood, and with the same materials 

 construct, if need be, a few partitions for separate 

 chambers. If, on occupying the residence, they should 

 perchance discover that part of the stump is already 

 inhabited by another ant colony, the latter are killed 

 or turned out without much ado. If they should fail 

 in this, they make peace and live on good terms with 

 the rivals, especially, if the latter are equal to them in 

 fighting strength, but differ greatly in size and means 

 of defense. The nests are separated by partitions, and 

 the stump is henceforth inhabited by a "compound 

 nest." 



Such "stolen nests" lorm a large category of ant 

 nests, particularly in places where there are many 

 stones; for almost all ant species that dwell in earth 



