H 6 .-1NTS. 



extent, for the apterous condition of their females. There is, however, 

 a passive displacement or dissemination of whole colonies in certain 

 species like the fire-ant (Solenopsis gcminata), which often nests in 

 low-lands subject to frequent and sudden inundations. Von Ihering 

 ( iX<)-j) has made the interesting discovery that when a nest of these 

 ants is flooded, they agglomerate to form a ball 16-25 cni - m diameter, 

 which encloses the brood in the center. This ball is borne along on the 

 surface of the water while its living units keep shifting their position 

 to avoid too prolonged immersion, till the shore or some projecting 

 rock or tree-trunk is reached, when the colony scrambles out of the 

 uncongenial element. I am informed by a gentleman from Louisiana 

 that this same ant resorts to the same method of saving its colonies in 

 the flooded bayous of the Southern States. Similar observations have 

 been made by Savage (1847) on the African driver ants (Anoinina 

 arccns] and by Ern. Andre (1885) on European ants. 



Finally, ant colonies or fertile female ants are often transported 

 by man from land to land as stowaways in the cargoes of ships and 

 railway trains. Every botanical garden annually receives several 

 species of these insects from the tropics in the pseudobulbs of orchids, 

 among the leaves of aroids or tillandsias, or in the soil and moss adher- 

 ing to the roots of plants, and some of the smaller species thus unin- 

 tentionally imported manage to establish themselves permanently in 

 the hot-houses. 



Owing to these various means of dissemination, the species of ants 

 have become more widely distributed than any other insects, with the 

 possible exception of the Diptera. Some of our American forms, for 

 example, Dorymyrmex pyramicus, range from Illinois to Argen- 

 tina. Many species, like Eciton caecum and Solcnopsis ^cjniiiata, are 

 coextensive with the tropical and subtropical portions of America, 

 and the latter also occurs in the tropics of the Old World. The 

 former, being a Doryline ant, does not occur in the West Indies. Still 

 other species, like Camponotus licrculcanits. Formica fnsca and san- 

 ^iiinea, extend over the whole north temperate portion of the globe, 

 and C. inacitlatns is represented by subspecies or varieties on every 

 continent and on many of the outlying islands. 



The distribution of ants may be studied either from a faunistic or 

 from an ethological point of view. In faunistic studies the emphasis 

 is placed on the areas or ranges covered by the various species, sub- 

 species and varieties and on the bearing of such distribution on the 

 genesis or descent of taxonomic groups as units. And since the exist- 

 ing fauna is unquestionably derived from previous faunas, which must 

 have determined its character and composition, we are compelled to 



