1907.] Wheeler, Fungus-grounng Ants of North America. 695 



fertilized female "rids herself of her easily detached wings by quick motions 

 of her legs and then begins to dig her burrow in some spot more or less free 

 from vegetation. This canal is nearly or quite vertical and measures about 

 12-15 mm. in diameter. It is so narrow that the '19a' cannot turn around 

 in it, but is compelled to walk backwards whenever she returns to the surface. 

 She bites off lumps of earth with her powerful jaws, makes them into a 

 pellet by means of loose threads of saliva, brings them up and deposits them 

 a short distance from the entrance to the burrow. The earth thus brought 

 up forms a circular wall, thickened in front and interrupted behind, about 

 4-5 cm. broad in front and at that point 3 cm. from the entrance. The 

 burrow varies from 20-30 cm. in length according to circumstances and 

 ends in a small laterally placed chamber about 6 cm. long and somewhat 

 less in height. As soon as the chamber is completed, the ant closes the upper 

 portion of the burrow to a distance of 8-10 cm. from the entrance with 

 pellets of earth and this closure becomes more and more compact in the 

 course of weeks, probably through the action of the rain. If the nest be 

 opened in one or two days, the female will be found in the empty chamber 

 unchanged, only more lethargic, as if exhausted. A few days later one finds 

 near the ant a little packet of 20-30 eggs undergoing segmentation. Beside 

 them lies a flat heap of loose white substance, only 1-2 mm. in diameter. 

 This is the earliest rudiment of the fungus garden. Microscopical examina- 

 tion shows that it consists of compact masses of the well-known fungus- 

 hyphae, but without traces of "kohlrabi" corpuscles. As time goes on the 

 fungus garden grows rapidly and becomes more voluminous till it reaches a 

 diameter of about 20 cm. It seems to consist of closely aggregated spherules 

 about 1 mm. in diameter. As soon as it has attained this size the transparent 

 pyriform globules bud out, which Moeller called 'kohlrabi' and the ant is 

 seen to eat them frequently. She always keeps close to the fungus garden 

 and in it embeds her eggs. The larger of these soon become larvje. The 

 eggs are not spun over with fungus hyphae but have the chorion smooth and 

 shining. Eggs are also found in the interior of the fungus mass, which the 

 ant keeps rearranging and redistributing from time to time. It was easy, 

 for purposes of observation, to transfer the ant to a terrarium. Without 

 excavating anew she remained with her garden on the fresh layer of cai-th. 

 The garden did not grow, but rather diminished in volume, for it is difHcult 

 to imitate the conditions, especially the precise degree of moisture, in which 

 it grows and develops in its cavity. I failed therefore to keep the ant and 

 her garden till the first workers appeared. The time retjuired to accomplish 

 this must be between two and three months. Presumably the last phase 

 of this first brood period is very precarious, since leaves must be brought 

 in to serve as a substratum for the further growth of the fungus garden. 



