DO ANTS FORM PRACTICAL JUDGMENTS? 337 



While these one to four workers were busy covering the cracks 

 surrounding compartment C, yet others were busy filling com- 

 partment A (Fig. 1) with trash. A large number of workers 

 assisted in filling compartment A, hence it was not long before 

 this compartment was almost completely filled with trash and the 

 entrance E so reduced in size that it was necessary to enlarge the 

 opening whenever occasion arose to carry large pieces of captured 

 food to those within the nest. 



On an adjacent island I had a colony of the same species of 

 ants in which there were no fertile females. In the early part of 

 May these neuters began to lay eggs. Immediately compart- 

 ment A was filled with trash. 



Since the glass covering compartment A is colorless we must 

 look upon the detritus placed there as trash heaped about the 

 entrance to the nest. That the formation of such a trash pile 

 about the opening of the nest is a common breeding habit or in- 

 stinct is evidenced by the fact that in nature trash piles are found 

 about the openings of many of the nests of this species. In the 

 early spring I have frequently noticed such trash piles in the proc- 

 ess of formation. They are composed partly of dirt brought 

 from within the nest and partly of trash gathered from the sur- 

 rounding territory. In a region where this species of ants is 

 common, a careful search in the early spring is certain to reveal 

 several such trash piles in the process of construction. In almost 

 every case observed by me, a few ants were busy collecting trash 

 from the outside and dropping it about the nest opening, while a 

 larger number of ants were bringing dirt from the interior and 

 heaping it about the same opening. It would then be illogical 

 to consider the trash stored away in compartment A as anything 

 more than the homologue of the trash pile that this species 

 frequently builds about the entrance to its normal nests. 



To me it does not seem logical to group the four piles of trash 

 covering crack b and the edges c, d, /(Fig. i) in the same cate- 

 gory, for neither of these trash piles surrounded an entrance into 

 the nest : b, the nearest of these piles, was at least seven inches 

 from E, which was the only opening into the nest. Since this 

 colony and its immediate ancestors had lived for several genera- 

 tions under the paving stones mentioned it is unlikely that either 



