1874.] Tropical Zoology. 329 
simulates a black, stinging ant. Spiders are greatly sought 
after and eagerly devoured by birds, whilst stinging ants are 
little relished. The Heliconii, a group of butterflies very 
largely developed in the West Indies and in Central America, 
have in all probability an offensive flavour. Birds, monkeys, 
and spiders avoid or reject them. ‘There are other butterflies, 
belonging to perfectly distinct groups, which closely simulate 
the Heliconii, and thus escape the beaks of birds and the 
attention of spiders. The advocates of evolution explain 
this mimetism by supposing that, ¢e.g., a bug by some acci- 
dental variation from the normal structure of its congeners 
received a slight resemblance to a hornet. Its posterity, to 
whom this resemblance was transmitted, enjoyed an ad- 
vantage in the struggle for existence over bugs which had 
remained true to the pristine type. Those of them in which 
the likeness to the hornet was most pronounced would, again, 
escape best from their enemies, and would thus have the 
greatest chance of becoming the progenitors of the next 
generation. The opponents of evolution have no way of 
accounting for mimetism beyond asserting that certain 
species were, for their protection, arbitrarily and ab initio 
endowed with these resemblances,—a most unsatisfactory 
explanation. 
The same do¢trine throws light on the difficulties often 
experienced in introducing foreign plants into any country. 
Thus the orange and the citron, in Central America, are very 
much more exposed to the attacks of Ecitons than any 
native vegetation. The reason is very simple :—‘‘ Through 
long ages the trees and the ants of tropical America have 
been modified together. Varieties of plants that arose un- 
suitable for the ants have had an immense advantage over 
others that were more suitable, and thus—through time— 
every indigenous tree that has survived has done so because 
it has had originally, or has acquired, some protection 
against the great destroyers. The leaf-cutting ants are con- 
fined to tropical America, and we can easily understand that 
trees and vegetables introduced from foreign lands, where 
these ants are unknown, could not have acquired—except 
accidentally and without reference to the ants—any protec- 
tion against them.” 
If we reject the Darwinian view we should naturally infer 
that in any country foreign trees would enjoy an immunity 
from indigenous depredators, instead of being, as they are, 
especially singled out for attack. It is a curious fact that 
the leaf-cutting ants form, with the vegetable matter they 
thus carry off, manure-heaps, on which they cultivate minute 
fungi for the food of their larve. 
