466 
Following Bates’ work in South 
America, Alfred Russell Wallace de- 
veloped the theory for the butterflies 
of the Indo-Malayan region, and Tri- 
men for those of Africa. In each in- 
stance abundant cases of supposed 
minicry were found. 
MULLER’S CONTRIBUTION 
oe 
We may now turn to one of the 
most ingenious developments of the 
theory of mimicry. Not long after 
Bates’ original memoir appeared at- 
tention was directed to a group of cases 
which could not be explained on the 
simple hypothesis there put forward. 
Many striking cases of resemblance had 
been adduced in which both species 
obviously belonged to the presumably 
unpalatable groups. Instances of the 
sort had been recorded by Bates him- 
self and are perhaps most plentiful in 
South America between species belong- 
ing respectively to the Ithomiinae 
and Heliconinae. On the theory of 
mimicry all the members of both of 
these groups must be regarded as 
specially protected owing to their con- 
spicuous coloration and distasteful prop- 
erties. What advantage, then, can an 
Ithomiine be supposed to gain by 
mimicking a Heliconine, or vice versa? 
Why should a species exchange its own 
bright and conspicuous warning pattern 
for one which is neither brighter nor 
more conspicuous? To Fritz Miller, 
the well-known correspondent of Dar- 
win, belongs the credit of having sug- 
gested a way out of the difficulty. 
“Miuller’s explanation turns upon 
the education of birds. Every year 
there hatch into the world fresh genera- 
tions of young birds, and each genera- 
tion has to learn afresh from experience 
what is pleasant to eat and what is 
not. They will try all things and hold 
fast to that which is good. They will 
learn to associate the gay colors of 
the Heliconine and the Ithomiine with 
an evil taste” and they will thenceforth 
avoid butterflies which advertise them- 
selves by means of these particular 
color combinations. But in a locality 
by the supporters of the mimicry theory. 
the supposition.” 
The Journal of Heredity 
where there are many models, each with 
a different pattern and color complex, 
each will have to be tested separately 
before the unpalatableness of each is 
realized. If, for example, a thousand 
young birds started their education on 
a population of butterflies in which there 
were five disagreeable species, each 
with a distinct warning pattern, it is 
clear that 1,000 of each would devote 
their lives to the education of these 
birds, or 5,000 butterflies in all. But if 
these five species, instead of showing 
five distinct warning patterns, all dis- 
played the same one, it is evident that 
the education of the birds would be 
accomplished at the price of but 1,000 
butterfly existences instead of five. 
Even if one of the five species were far 
more abundant than the others, it 
would yet be to its advantage that the 
other four should exhibit the same warn- 
ing pattern. Even though the losses 
were distributed pro rata the more 
abundant species would profit to some 
extent. For the less abundant species 
the gain would, of course, be relatively 
greater. Theoretically, therefore, all 
of the five species would profit if in 
place of five distinct warning patterns 
they exhibited but a single one in com- 
mon. And since it is profitable to all 
concerned, what more natural than that 
it should be brought about by natural 
selection?” 
TWO TYPES OF MIMICRY 
There are thus two generally accepted 
types of mimicry—the Batesian, where 
one species adopts the coloration of 
another, and the Miullerian, where a 
number of species adopt a common 
pattern. As to the facts, there is no 
room for dispute, but there is much 
room for dispute about the explanation 
of the facts. 
Wallace pointed out that there are 
five necessary conditions which must 
and do exist in any case of mimicry: 
1. That the imitative species occur 
in the same area and occupy the very 
same station as the imitated. 
2“In attributing this quality to the butterflies in question I am merely stating what is held 
I know of scarcely any evidence either for or against 
