Ants Growers of Mushrooms 63 
the formicarium, and huge fellows, measuring three-quarters 
of an inch in length, that only come out of the nest during a 
migration or an attack on the nest or one of the working 
columns, are seen stalking down with a determined air, as if 
they would soon right matters. As soon, however, as they 
have touched the sublimate, all their stateliness leaves them: 
they rush about; their legs are seized hold of by some of the 
smaller ants already affected by the poison; and they them- 
selves begin to bite, and in a short time become the centres 
of fresh balls of rabid ants. The sublimate can only be used 
effectively in dry weather. At Colon I found the Americans 
using coal tar, which they spread across their paths when any 
of 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 through- 
out tropical America, and have excited the attention 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 permitted 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 operations we also, on two occasions, 
carried our excavations from below up through very large 
formicariums, so that all their underground workings were 
