1879.] NATURAL SCIENCES OP PHILADELPHIA. 159 



The structure of a nest in natural site is obviously more diffi- 

 cult to stud}'. For the sake of comparison, one was taken which 

 was located on the edge of a brick walk. The walk was separated 

 from the grass-plat by a line of bricks set on edge. Several of 

 these and the adjoining flat bricks were removed, thus quite ex- 

 posing the fomicary to the depth in parts of four inches. The 

 side of the grass-plat against which the bricks had pressed was 

 pierced by many openings, one-quarter of an inch or more in diame- 

 ter, leading for the most part directly into ovoid chambers whose 

 longest diameters were from three-fourths of an inch to one inch 

 in length. One of the largest of these was close to the surface just 

 beneath the grass roots, and was filled with naked larvae of worker 

 ants, most of which were white, a few yellow. These chambers 

 had interior openings extending into the earth. They were united 

 together by galleries, where their boundaries did not interblend. 

 There was an opening directly upward into the grass, but the 

 main avenue for the carriage of excavated earth led downward to 

 the lower edge of the brick, then diagonally upward through the 

 earthen seam of that and the next brick, debouching at the surface 

 and upon the pavement. Openings downward communicated 

 with this avenue, as did also a broad (three-eighths inch) winding 

 track, which followed the under surface of the brick its entire 

 length, and beyond. These avenues presented the characteristics 

 of those in the artificial nest, but were larger and not so numerous. 

 The large larvae of several queens were found in the lower ave- 

 nues. 



The behavior of the ants placed in jar No. 3 was like that of 

 those in No. 2, i. e , the fighting soon ceased, and the work of 

 gallery digging began. Here, also, it could not be determined 

 whether the survivors were of one party or of both, but the latter 

 was inferred in view of the experiment which showed the inter- 

 blending of the harmonized hostiles of No. 1 with the survivors of 

 No. 2. The galleries here were not made against the surface of 

 the glass as in No. 2, but were confined apparently to the interior 

 of the earth, which they must have quite honey-combed, as shown 

 by the quantity of pellets brought up, and by the numerous open- 

 ings upon the surface. 



In this connection Mr. McCook referred to the economy in na- 

 ture of ants by contributing to the fertilization of the earth. A 

 comparison between the formicaries of various species shows that 

 all the mason ants substantially agree in (at least) subterraneous 

 nidification. The example presented of the underground work of 

 Tetramorium will give some idea of the manner in which the 

 earth may be excavated hy a single colon}'. In a portion of the 

 exposed surface, which presented less rather than more of the 

 average amount of excavation, the gallery surface was measured. 

 In a space of three square inches there were (approximately) one 

 and nine-sixteenths square inches of gallery surface, or about one- 



