ANT COMMUNITIES 



another, uniting the whole in a way that, perhaps, may 

 not be characterized as " do vetailing " or " ball-and- 

 socket" jointing, but which raises the suggestion of 

 such contrivances. 



It is said that formic acid, which is extruded freely 



*/ 



by ants, forms with silica a natural cement. Can it be 

 that these pellets, which are composed largely of sand, 

 are thus cemented together? Probably not; but at least 

 the moisture of the late rain has aided their adhesion. 

 Grass straws, cut from tufts growing along the base and 

 strewn over the summit of the cone, are dragged into place 

 and skilfully wrought in with the pellets. Besides these, 

 bits of decayed wood, the needle-like leaves of pine-trees, 

 which are abundant here, and leaves of low shrubs are 

 intermixed with the soil. These insect masons are not 

 forced to the hard service laid by the Pharaoh upon 

 ancient Israelites of making bricks without straw. 



At another hill the builders had undertaken a special 

 work of construction, or, rather, of repair. An errant 

 cow grazing on the mountain-slope we can hear the 

 tinkle of her bell from a distant corner of the wood- 

 had strolled by that way and set a hoof upon the edge 

 of the mound, leaving a deep and wide impression. Just 

 one; for a swarm of irate insects must have instantly 

 attacked Brindle's legs and caused her to beat a rapid 

 retreat. But she has left a footprint on the cone that 

 must needs be repaired. As a full day's work is before 

 us, let us bring camp-stool, note-book, and drawing-pad, 

 and sit down before it. We shall see something that 

 looks like a well-planned system of engineering in filling 

 up the hole. 



The cow's foot had made a nearly circular pit between 

 eight and nine inches in diameter and depth. At the 



38 



