h. V.] AXIS GROWERS OF MUSHROOMS. 79 



them led to their gardens. I was also told that the Indians 

 prevent them from ascending young trees by tying thick 

 wisps of grass, with the sharp points downwards, round 

 the stems. The ants cannot pass through the wisp, and 

 do not find out how to surmount it, getting confused 

 amongst the numberless blades, all leading downwards. 

 I mention these different plans of meeting and frustrating 

 the attacks of the ants at some length, as they are one of 

 the greatest scourges of tropical America, and it has been 

 too readily supposed that their attacks cannot be warded 

 off. I myself was enabled, by using some of the means 

 mentioned above, to cultivate successfully trees and 

 vegetables of which the ants were extremely fond. 



Notwithstanding that these ants are so common 

 throughout tropical America, and have excited the at- 

 tention of nearly every traveller, there still remains 

 much doubt as to the use to which the leaves are put. 

 Some naturalists have supposed that they use them 

 directly as food ; others, that they roof their underground 

 nests with them. I believe the real use they make of 

 them is as a manure, on which grows a minute species of 

 fungus, on which they feed ; that they are, in reality, 

 mushroom growers and eaters. This explanation is so 

 extraordinary and unexpected, that I may be per- 

 mitted to enter somewhat at length on the facts that 

 led me to adopt it. When I first began my warfare 

 against the ants that attacked my garden, I dug down 

 deeply into some of their nests. In our mining opera- 

 tions we also, on two occasions, carried our excavations 

 from below up through very large formicariums, so that 

 all their underground workings were exposed to obser- 

 vation. I found their nests below to consist of numerous 



