IV jNIVRMICIDES LEAF-CUTTING ANTS 167 



to make a subterranean tunnel in a straight line to a desired 

 object situated at so great a distance, we know not. 



The use .the leaf-cutting ants make of the enormous amount 

 of material they gather was for long a subject of debate, and has 

 only recently been ascertained by the observations of Moller. 

 Afber being carried to the nest the pieces of leaves are cut into 

 small fragments by another set of workers and formed into balls, 

 which are packed in various parts of the nest, and amongst 

 which the mycelium of a fungus — Rozites gongylopliora — ramifies. 

 This fungus the ants cultivate in the most skilful manner : 

 they manage to keep it clear from mouldiness and bacterial 

 agents, and to make it produce a modified form of growth in 

 the shape of little white masses, each one formed by an agglomera- 

 tion of swellings of the mycelium. These form the chief food of 

 the colony. Moller ascertained by experiment that the results 

 were due to a true cultivation on the part of the ants : when 

 they were taken away from the nests, the mycelium produced 

 two kinds of conidia instead of the ant-food. 



Many details of the economy of these leaf-cutting ants are 

 still very imperfectly known. The large-headed forms, called 

 soldiers, have been the subject of contradictory statements ; 

 Bates having concluded from his own observations that they 

 are harmless, while Mr. J. H. Hart assures us that they are very 

 fierce and vindictive, and inflict very serious wounds by biting 

 (the Attini do not sting). We anticipate that the observations 

 of both these naturalists will prove to be substantially correct, 

 and that the differences in habits will be found to be owing to 

 distinctions in the conditions of the community. In connection 

 with this point we may remark that the function of the ex- 

 cessively large heads of certain kinds of soldier-ants is still 

 obscure. In the East Indian Pheidologeton diversus the big 

 soldiers are quite one hundred times as large as the smaller 

 workers. As these latter bite viciously it would naturally be 

 supposed that their gigantic confreres with enormous heads would 

 be warriors of a most formidable nature ; but, as a matter of fact, 

 the giants are unable to bite even when they try to do so. 

 Aitken has somewhere suggested that these enormous individuals 

 play the part of state elephants ; and we have been informed by 

 Colonel Bingham that the small ants may frequently be seen 

 riding in numbers on their unwieldy fellows. We anticipate 



