Mimiery 59 
it, since the species would in any case be immune? In Eastern Brazil, 
for instance, there are four butterflies, which bear a most confusing 
resemblance to one another in colour, marking, and form of wing, 
and all four are unpalatable to birds (Figs. 1—4). They belong to 
four different genera and three sub-families, and we have to inquire: 
Whence came this resemblance and what end does it serve? For a 
long time no satisfactory answer could be found, but Fritz Miiller’, 
seventeen years after Bates, offered a solution to the riddle, when 
he pointed out that young birds could not have an instinctive 
knowledge of the unpalatableness of the Ithomiines, but must learn by 
experience which species were edible and which inedible. Thus each 
young bird must have tasted at least one individual of each inedible 
species and discovered its unpalatability, before it learnt to avoid, and 
thus to spare thespecies. But if the four species resemble each other 
very closely the bird will regard them all as of the same kind, and 
avoid them all. Thus there developed a process of selection which 
resulted in the survival of the Ithomiine-like individuals, and in so 
great an increase of resemblance between the four species, that they 
are difficult to distinguish one from another even in a collection. 
The advantage for the four species, living side by side as they do e.g. 
in Bahia, lies in the fact that only one individual from the mimicry- 
ring (“inedible association”) need be tasted by a young bird, instead 
of at least four individuals, as would otherwise be the case. As the 
number of young birds is great, this makes a considerable difference 
in the ratio of elimination. The four Brazilian species are figured 
on the accompanying plate (Figs. 1—4): Lycorea halia (Danainae), 
Heliconius narcaea (eucrate) (Heliconinae), Melinaea ethra, and 
Mechanitis lysimnia (Ithomiinae). 
These interesting mimicry-rings (trusts), which have much signi- 
ficance for the theory, have been the subject of numerous and careful 
investigations, and at least their essential features are now fully 
established. Miiller took for granted, without making any investi- 
gations, that young birds only learn by experience to distinguish 
between different kinds of victims. But Lloyd Morgan’s’ experiments 
with young birds proved that this is really the case, and at the same 
time furnished an additional argument against the Lamarckian 
principle. 
In addition to the mimicry-rings first observed in South America, 
others have been described from Tropical India by Moore, and by 
Poulton and Dixey from Africa, and we may expect to learn many 
more interesting facts in this connection. Here again the preliminary 
postulates of the theory are satisfied. And how much more that 
would lead to the same conclusion might be added! 
1 In Kosmos, 1879, p. 100. 2 Habit and Instinct, London, 1896. 
