136 



THE FACTORS 



[Part I 



unserviceable. Not only leaves, but also flowers, fruits, and seeds, or 

 portions of them, are carried home. 



The parasol-ants disappear with their booty through the entrance-holes 

 to their nest, which lies either in a shallow natural cavity, as in the case 

 of the very carefully investigated Atta discigera and A. Hystrix of South 

 Brazil, or is dug in the ground, as in the case of Atta coronata and 

 probably of most species. What becomes of the pieces of leaves that 

 are brought home in such large quantities has until recently remained 

 an unsolved problem. Bates considered that they were used for lining 

 walls ; MacCook thought they were for the preparation of a kind of 

 paper for internal constructions ; Belt, however, advanced the daring 

 hypothesis that the ants cultivated fungi on the decomposing masses 



VRC: 



FlG. 73. A fungus-garden prepared on a plate in three days by hairy ants (Apterostigma IV 

 mentioned in the text on p. 138) in confinement. Natural size. After Alf. Moller. 



of leaves. The sagacious ' Naturalist in Nicaragua ' had, as usual, hit 

 on the right explanation. Alf. Moller, in a research that presents a 

 rare instance in the domain of oecology of acuteness combined with 

 the critical faculty, has definitely proved the correctness of Belt's often- 

 disputed and derided statement, ' I believe . . . that they are in reality 

 mushroom-growers and eaters.' 



The imported pieces of leaves serve only to a small extent for covering 

 the nests. Most of them are cut up again by the ants and kneaded 

 soft by their feet and mandibles, so that but few cells remain unbruised. 



