60 The Naturalist in Nicaragua 
we can easily understand that trees and vegetables intro- 
duced from foreign lands where these ants are unknown 
could not have acquired, excepting accidentally, and with- 
out any reference to the ants, any protection against their 
attacks, and now they are most eagerly sought by them. 
Amongst introduced trees, some species of even the same 
genus are more acceptable than others. ‘Thus, in the orange 
tribe, the lime (Cztrus lemonum) is less liked than the other 
species; it is the only one that I ever found growing really 
wild in Central America: and I have sometimes thought 
that even in the short time since the lime was first intro- 
duced, about three hundred years ago, a wild variety may 
have arisen, less subject to the attacks of the ants than the 
cultivated variety; for in many parts I saw them growing 
wild, and apparently not touched. The orange (Cuztrus 
aurantium) and the citron (Citrus medicus), on the other 
hand, are only found where they have been planted and 
protected by man; and, were he to give up their cultivation, 
the only species that would ultimately withstand the attacks 
of the ants, and obtain a permanent footing in Central 
America, would be the lime. The reason why the lime is 
not so subject to the attacks of the ants is unknown; and 
the fact that it is so is another instance of how little we know 
why one species of a particular genus should prevail over 
another nearly similar form. A little more or less acridity, 
or a slight chemical difference in the composition of the 
tissues of a leaf, so small that it is inappreciable to our 
senses, may be sufficient to ensure the preservation or the 
destruction of a species throughout an entire continent. 
The ravages of this ant are so great that it may not be 
without interest for me to enter upon some details respecting 
the means I took to protect my own garden against their 
attacks, especially as the continual warfare I waged against 
them for more than four years made me acquainted with 
much of their wonderful economy. 
In June 1869, very soon after the formation of my garden, 
the leaf-cutting ants came down upon it, and at once com- 
menced denuding the young bananas, orange, and mango 
trees of their leaves. I followed up the paths of the invading 
hosts to their nest, which was about one hundred yards dis- 
tant, close to the edge of the forest. The nest was not a 
