100 Chapter III. 



species, e. g., between ants and* their guests, such as 

 the club-bearing beetles (Claviger), the tufted beetles 

 {Lomechusa, Atemeles), etc. But even those cavities 

 of plants, which are properly not meant to receive and 

 to lodge ants, are often occupied by them, especially 

 in the luxuriant vegetation of tropical South America. 

 Aug. Forel in the winter of 1895 and 1896 visited 

 the savannas of Columbia, where he found that the 

 nests of by far the most of the species, belonging to 

 eight different genera, were built in dry stalks of grass.^ 

 This led him to think that in the prairies and forests of 

 tropical America the nests in stalks and in hollow parts 

 of plants were the typical form of ant nests, correspond- 

 ing to the climate of that country, whereas in our 

 zones the usual type is the earth nest or else the hill 

 made of earth and parts of plants. 



This pursory comparison of the various forms^ of 

 nests met with in different ant species, shows clearly 

 enough, that their character is conditioned by the 

 peculiar shape of the bodily organs of the builders , but 

 far less than is the case with most of the other artistic 

 instincts in insects and other animals. The form of 

 the mandibles, the presence of salivary glands with 

 gluey secretions or of real spinning glands, indicate 

 only the general outline of the architectural style 

 preferred by their owners. Only the different instinc- 

 tive dispositions of the builders determine more 

 exactly the specific differences of their nest forms. 



*) "Quelques particularites de I'habitat des fourmis de TAmerique 

 tropicale" (Extr. des Ann. de la Soc. Entom. Belg., XL [1896], 167 ss.) 

 and "Zur Fauna und Lebensweise der Ameisen im columbischen 

 Urwald," in "Mittei!. der Schweiz. Entomol. Gesellsch.," IX, 9th issue, 



2) Forel, "Die Nester der Ameisen," Zuerich, 1892. 



