INSECTS AND CIVILIZATION 



form the arable surface of the earth. Before Dr. Dar- 

 win's book on earth worms had been printed, the author 

 had made and printed in the Proceedings of the Academy 

 of Natural Sciences of Philadelphia^ some observations 

 upon the action of ants in forming and shifting the top- 

 soil, and in keeping the surface open for aeration and the 

 absorption of moisture. The observations were made 

 upon two species, the pavement ant (Tetramorium 

 ccespitum) and a little brown Lasius that, in some quar- 

 ters at least, is popularly known as the meadow ant. 

 The pavement ant abounds in the open spaces of cities 

 and towns, and especially affects the warm layers of soil 

 underneath the brick and flag pavements of sidewalks. 

 It is a pugnacious creatureling, and its battles with 

 neighboring communities of congeners are as frequent, 

 as fatal, and apparently as foolish as are most human 

 wars. Several formicaries of this ant were put under 

 observation in the early part of the year when the work- 

 ers are most busy enlarging their nests for the prospective 

 increase of their communities. The quantity of earth 

 brought up through the chinks of a brick walk, and from 

 various parts of the lawn, was collected at frequent inter- 

 vals. It was carefully weighed and measured, and a 

 calculation made of the amount added to the top-soil by 

 an average formicary within a specified time. The calcu- 

 lation was applied to a number of ants' nests, with results 

 not greatly differing, but upon a much narrower field, 

 from those reached by Darwin from the labors of earth 

 worms. This may seem to be a small matter, and per- 

 haps it is, under present conditions, which so greatly 

 limit emmet operations by man's cultivation of the soil. 



^Proceedings (1879), pp. 1.59-161. 

 293 



