NATURAL HISTORY. 131 



serve as passage-ways. The tops of these 

 large halls are covered with an arched ceiling, 

 and this ceiling is held up, sometimes by little 

 columns, sometimes by very thin walls, or by 

 props built against the side walls, just like but- 

 tresses. There are also chambers which have 

 but one door, which opens into the lower 

 story, and large open places in the centre of 

 the nest something like a cross road, and all 

 these little galleries or streets come into that 

 open place." 



" Any bridges, Uncle Philip ?" 



" No, boys ; no bridges among these ants, so 

 far as I know. There will sometimes be as 

 many as twenty stories above ground in the 

 ant-hill, and as many below. The best time 

 to see these little fellows at work is in a gentle 

 shower of rain, or directly after." 



"Why do they work in the rain, Uncle 

 Philip?" 



" I suppose, boys, it is because the earth is 

 then better for them ; and one thing that has 

 been noticed about their work is, that the rain, 

 when it is not too violent, seems to make it 

 solid, for these ants have no gum or glue 

 about them like some other insects, to make 

 the>?artri stick together. As soon as the rain 



