854 THE AMERICAN NATURALIST. (Vor. XXXIV. 
More recently Forel has studied the habits of two other spe- 
cies (Atta cephalotes L. and A. sexdens L.) in Colombia! He 
seems to have given some attention to the róle performed by 
the different casts of worker ants — casts which are also repre- 
sented in our Atta fervens — in this process of collecting and 
comminuting the leaves and in cultivating the mushroom. At 
p. 31 he says: “The largest workers (soldiers) triturate the 
leaves and defend the nest. They draw blood when they bite. 
The indigenes are said to use these insects for closing wounds. 
They induce them to bite the two lips of the wound and there- 
upon sever the bodies from the heads, which then serve as a 
suture. The medium-sized workers cut the leaves from the 
trees, while in the nest the workers of the minim cast are for- 
ever clipping the threads of the mycelium of the Rhozites, 
which then develops the * Kohlrabi,’ on which the ants feed." 
The shape of a mushroom garden is that of a discoidal 
sponge. On its upper surface the ants pile up the flocculent 
vegetable débris, threaded in all directions with fungus hyphze, 
in the form of thin, vertical, anastomosing plates, so that as 
much surface as possible is exposed to the atmosphere of the 
chamber. This atmosphere must contain a great amount of 
carbon dioxide and a very small amount of oxygen. The pecu- 
liar appearance of the surface of two large gardens is shown 
in the photographs (Figs. 1 and 2, about X4 the natural size). 
Although these gardens of Atta fervens closely resemble those 
of the South and Central American species observed by Möller 
and Forel, I have seen fit to figure them, both because Móller's 
work is out of print and may not be readily accessible to the 
reader, and because, to my knowledge, the gardens of our 
Texan leaf-cutter have not been figured heretofore. The ants 
leave several tubular or funnel-shaped openings (clearly shown 
in the figures), varying in diameter, and extending down into 
some chambers excavated in the base of the vegetable mass. 
In these chambers lives the huge queen of the colony, — an 
insect nearly an inch long, — the newly fledged males and vir- 
gin queens, together with the larvae, pupae, and attendant ants. 
1 Biologia Centrali-Americana Hymenoptera. Formicidæ (1899-1900), PP. 3! 
et seq. 
