686 Bulletin American Museum of Natural History. [Vol. XXIII, 



are stiil present, they are rescued. The last resort is the vertical wall of the 

 glass, up which the insects creep and where they huddle together, while over 

 the wide plain of the garden the fungus proceeds to the conidia-producing 

 stage." 



Moeller next undertook to determine the systematic position of the fungus. 

 He naturally supposed that the discovery of the fruiting form would show it 

 to be an asco- or basidiomycete. Although he failed to raise either of these 

 forms from his mycelial cultures he succeeded on four occasions in finding 

 an undescribed agaricine mushroom with Avine-red stem and pileus growing 

 on extinct or abandoned Acromijrmex nests. From the basidiospores of this 

 plant which he called Rozites gongi/lophora, he succeeded in raising a myce- 

 lium resembling in all respects that of the ant gardens. Three of the species 

 of Acromyrmex did not hesitate to eat portions both of this mycelium and 

 of the pileus and stem of the Rozites. He believed therefore that he had 

 definitively established the specific identity of the fungus cultivated by the 

 ants. 



The species of Apterosfigma investigated by ]\Ioeller usually nest in 

 cavities in rotten wood which is often also inhabited by other insects. The 

 fine wood castings and excrement of these insects are used by the ants as 

 material with which to construct their fungus-gardens. A. wasmanni con- 

 structs the largest nests, and it is only in the gardens of this species that the 

 mycelium produces structures analogous to the "kohlrabi heads" and 

 "clusters" of Acromijrtne.v. The heads, however, are club-shaped instead 

 of spherical dilatations of the hyphfe. As it produces only irregular swellings 

 on the hyphfe INIoeller believes that Apterostigma represents a much lower 

 stage in fungus-culture than the species of Acromyrme.v. The Apterostigma 

 are, however, very adaptable since they readily collect caterpillar excrement 

 or even farina and incorporate these substances into their gardens. Moeller 

 states that all the species of this genus cultivate the same fungus, which 

 must be a distinct species as the ants will not eat the fungus grown by Acro- 

 mijrme.v. The gardens of pilosum, mo;Ueri and another undetermined 

 Apternstigma, which live in small colonies of only 12 to 20 individuals, are 

 suspended from the roofs of the small cavities, 3 to -i cm. in diameter, in 

 the rotten wood and exhibit a peculiar structure not seen in other Attii. 

 "The garden is often completely, or at least nearly always in great part, 

 enclosed in a Avhite cob-web-like membrane. It was often possible to obtain 

 a view of uninjured nests of .1. pilosum that had been excavated in clefts 

 of the rotten wood. In such cases the envelope enclosed the whole fungus 

 garden like a bag with only a single orifice or entrance. The envelope is 

 attached in a pendent position to the surrounding wood, roots or particles 

 of earth by means of radiating fibres, and this explains why the gardens 



