LEAF-CUTTING ANTS AND FUNGI 



59 



They liave cut the pieces of leaves from some plant, probably a 

 shrub, and are taking them to their nest. Often they entirely strip 

 a shrub of its leaves within a few minutes. They will chew the jmcccs 

 of leaves into a pulp and spread out the pulp on an ar(>a i)reviously 

 cleaned for the purpose. On this leaf pulp the ants })lant the 

 mycelium (or spawn) of a mushroom. The workers now take con- 

 stant care of their mushroom garden, weeding out undesirable fungi, 

 and producing, therefore, almost a pure culture of the fungus that 

 was planted. 



The fungus that is grown by the leaf-cutting ants is Rozites 

 gongylopJiora, a toadstool-shaped mushroom. The ants, however, 



«,^*^^/ 



^^ :^^ *r. 



i^- 



:?=^?x?:?«^ 



"S 



-j'S'SISiii -^3ki. 



Fig. 22. — An example of antagonistic nutritive disjunctive symbiosis. 



do not permit the plant to produce mushrooms, which are its fruits. 

 Cultivation for many generations, perhaps for centuries, has caused 

 this fungus to produce abnormal vegetative structures just as many 

 of the plants cultivated by man do. These abnormal structures con- 

 sist of club-like, upward-projecting outgrowths of the mycelium 

 and are called kohlrabies because their abnormal nature makes them 

 comparable to the garden vegetable of the same name. The kohl- 

 rabies serve as food for the ants. This cultivation of mushrooms by 

 ants is entirely comparable to the cultivation of vegetables by man 

 and like the latter is an example of antagonistic nutritive disjunctive 

 svmbiosis. 



