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Moeller 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 wine-red stem and pileus growing in extinct or abandoned Acromyrmex nests. From the basidiospores of this plant, which he called Rhozites gongylophora, he succeeded in raising a mycelium resembling in all respects that of the ant gardens. Three of the species of Acromyrmex did not hesitate to eat portions of this mycelium and of the pileus and

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(Original.)

FIG. 195. Vestigial nest crater of Trachymyrmex septentrionalis. The nest entrance is at x, the pile of sand pellets shown in the lower right-hand corner represents the crater of Atta texana and Mallerius versicolor.

stem of the Rhozites. He believed, therefore, that he had definitively established the specific identity of the fungus cultivated by the ants. A careful perusal of Moeller's observations shows an important lacuna at this point. That his Atte ate portions of the pileus and stem of the Rhozites does not prove that it is the fruiting form belonging to the fungus they habitually cultivate and eat. Nor is Moeller on much surer ground when he assumes that the mycelia cultivated by different

genera of Attii belong to different species of fungi, for it is very prob able that the ants of one species would avoid fungus taken from the nest of another on account of the alien nest-aura. Certainly, to the human olfactories, the fungus gardens of Atta texana have a very

striking odor which is altogether lacking in the gardens of Trachymyrmex, and it would be strange if these differences did not affect the appetites of such sensitive insects as the ants, In my opinion, it is not improbable that the fungi cultivated by the ants. may be more closely related to the moulds (Ascomycetes) than to the mushrooms (Basidiomycetes). Moeller does, in fact, call attention to certain Ascomycete peculiarities in the mycelium cultivated by Acromyrmex discigera. This is a matter, however, to be settled by the mycologist, and I merely call attention to it in this connection, because Moeller's somewhat guarded statements have assumed an unduly positive form in subsequent reviews of his work. The species of Apterostigma investigated by Moeller 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 constructs 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 Acromyrmer. The "heads," however, are club-shaped instead of spherical dilations of the hyphæ.

FIG. 196. Diagram of a large nest of a southern variety of Trachymyrmex septentrio

nalis, showing near the surface the small original chamber of the queen, five chambers with pendent fungus gardens, and a newly excavated chamber in which the garden has not yet been started. (Original.)

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The gardens of pilosum, mælleri and of another undetermined Apterostigma, which live in feeble colonies of only twelve to twenty individuals, are suspended from the roofs of the small cavities, 3 to 4

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 white cobweb-like membrane. It was often possible to obtain a view of uninjured nests of A. 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 fibers, and this explains why the gardens are so easily torn asunder while the nest is being uncovered." Even in captivity these ants persisted in hanging their gardens to the sides of the glass dishes in which they were kept.

The two species of Cyphomyrmex observed by Moeller were found nesting under bark or in rotten wood like Apterostigma. The largest gardens of C. strigatus are only 8 cm. long, whereas those of C. auritus may attain a length of 15 cm. and a breadth and height of 5 cm. These gardens are never pendent and never enclosed in a mycelial envelope. In other respects they resemble those of Apterostigma and are grown on the same substrata.

FIG. 197. Worker of Mællerius versicolor of Mexico, Texas and Arizona. (Original.)

Moeller's studies were confined to the adult colonies of the Attii. The question as to how these ants came by their fungi in the first place, was subsequently answered by the researches of Sampaio (1894), von Ihering (1898), Goeldi (1905a and b) and Huber (1905, 1907, 1908). Sampaio found fungus gardens in very young formicaries of the Brazilian Atta sexdens, and von Ihering showed that the virgin female of this species, on leaving the nest for her marriage flight, carries in her infrabuccal pocket a pellet of hyphæ taken from the fungus garden of the maternal formicary. This pellet is the unexpelled refuse of her last meal. After fecundation she digs a cavity in the soil, closes its opening to the outside world and sets to work to found a colony. She spits out the pellet of hyphæ and cultivates it, while she is at the same time laying eggs and rearing the larvæ. Von Ihering and Goeldi maintain that she crushes some of her eggs and uses them as a substratum for the incipient fungus garden. J. Huber

describes the behavior of the young queen in greater detail and is able to trace the development of the colony up to the hatching of the first brood of workers. He finds that the female expels the pellet from her buccal pocket the day following the nuptial flight. It is a little mass .5 mm. in diameter, white, yellowish or even black in color, and consists of fungus hyphæ imbedded in the substances collected from the ant's body by means of the strigils on her fore feet and thence deposited in her mouth. By the third day six to ten eggs are laid. At this time also the pellet begins to send out hyphæ in all directions. The female separates the pellet into two masses on this or the following day. For the next ten to twelve days she lays about ten eggs daily, while the fungus flocculi grow larger and more numerous. At first

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FIG. 198. Nest craters of Mallerius versicolor in a sandy "draw" in the deserts of Arizona. (Original.)

the eggs and flocculi are kept separate, but they are soon brought together and at least a part of the eggs are placed on or among the flocculi. Eight or ten days later the flocculi have become so numerous that they form when brought together a round or elliptical disk about I cm. in diameter. This disk is converted into a dish-shaped mass with central depression in which the eggs and larvæ are thenceforth kept. The first larvæ appear about fourteen to sixteen days after the Atta

female has completed her burrow, and the first pupæ appear about a month after the inception of the colony. At this time the fungus garden has a diameter of only 2 cm. There are no "kohlrabi" corpuscles in the earlier stages, and when first seen they are at the periphery of the disk. A week later the pupæ begin to turn brown and in a few days the first workers hatch. Hence the time required for the establishment of a colony under the most favorable conditions is about forty days. After this rapid survey of the matter, Huber asks the important question: How does the Atta female manage to keep the fungus alive and growing? Obviously the small amount of substance in the original pellet must soon be exhausted and the growing hyphæ must

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FIG. 199. Male, deälated female, soldier and series of workers of Atta texana; natural size. (Photograph by A. L. Melander and C. T. Brues.)

be supplied with nutriment from some other source. His interesting answer to this question may be given in his own words: "After carefully watching the ant for hours she will be seen suddenly to tear a little piece of the fungus from the garden with her mandibles and hold it against the tip of her gaster, which is bent forward for this purpose. At the same time she emits from her vent a clear yellowish or brownish droplet which is at once absorbed by the tuft of hyphæ. Hereupon the tuft is again inserted, amid much feeling about with the antennæ, in the garden, but usually not in the same spot from which it was taken, and is then patted in place by means of the fore feet. The fungus then sucks up the droplet more or less quickly.

Often several of these

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