and we must be content, for the present, to examine and to test, 
by every means in our power, those explanations that have from 
time to time been offered. The fuller our knowledge of the facts to 
be accounted for, the more nearly true is our interpretation likely 
to be; and this is the justification for reviewing in some detail any 
kind of evidence that may have a bearing on the question before 
us. And I will ask my audience to be good enough to observe that, 
when I use the term « mimicry », I do so at present, as the lawyers 
say, « without prejudice ». 
Many cases of mimicry between Insects of different orders have 
long been known. The very remarkable resemblance borne by 
certain Mothsto some of the stinging Hymenoptera long ago attract- 
ed the attention of observant naturalists. BOISDUVAL drew atten- 
tion to the fact that three Butterflies belonging to three different 
families, namely Limnas chrysippus, the female of Hypolímnas 
misippus, and the trophonius-form of the female of Papilio darda- 
nus, show a close resemblance to each other in outward aspect. Of 
late years very numerous instances of a Similar kind have come to 
light. Sometimes the observed resemblance occurs between Insects 
of the same order but of different families, as between the Papilios 
and Pierines among the Butterflies; e. g., Papilio nephalion and 
Euterpe rosacea; sometimes between Insects of different orders. We 
find, for example, Ants mimicked by Hemiptera, Homoptera and 
Orthoptera, while other ZZymenoptera are closely copied by two- 
winged Flies. It is needless to multiply instances of this sort, for 
numbers of them must be familiar to all working naturalists. And 
when the extraordinary prevalence of this phenomenon is once real- 
ised, it becomes impossible to dismiss the question as being 
merely a matter of coincidence. If we had only a few such instan- 
ces to consider, we might be justified in calling them accidental. 
But, apart from other reasons, their very number raises the impro- 
bability of such an interpretation to so high a pitch as practically 
to forbid its acceptance. 
Let us look at the facts a little more closely. We have seen that 
some of the nearest resemblances occur between Insects of different 
orders. We may therefore dismiss at once the idea that the like- 
ness is merely due to affinity. At the same time there is no doubt 
that the element of affinity does to some extent enter into the 
question. We shall return to this point later. 
A short examination of cases will show us that the mimicry is 
often confined to the female sex. It is well known that in the 
instances mentioned just now it is only the female of Hypolimnas 
