554 



ANTS. 



degree of moisture in the >oil usually chosen as the habitat of the spe- 

 cies. The sponge- ;ire kept clean by weekly washing and an occasional 

 immersion in alcohol. Sponges of fine, tough texture render the best 

 service, as they offer no apertures where the ants may conceal their 

 eggs. The flake of sponge is so thin as to permit the ants to pa-- 

 between it and the roof-pane. 



' The completed nest is less than half an inch, or thirteen milli- 

 meters, in its interior height, and does not exceed three-fourths of an 

 inch, or two centimeters, in 'its exterior height. A low-power lens is 

 easily focused upon the ants within the nest." 



.Miss Fielde makes her nests of such sizes as to fit snugly into the 



** 



FIG. 285. Portable case showing three Fielde nests on shelves. (Photograph by 



J. G. Huhhard and Dr. O. S. Strong.) 



shelves of a portable box like the one represented in the figure (Fig. 

 285). This box has an interior length of seventeen inches, a width of 

 seven inches and a height of four and three-fourth inches. In a case 

 of these dimensions a number of nests can be carried safely for long 

 distances. 



I have used with considerable success a combination of the Janet 

 and Fielde nests. The glass base and sides of the latter are replaced 



