422 Mr. R. Meldola on Mimicry between 
blance of these two species,” we can only admit the mimetic 
theory in Fritz Miiller’s sense, and the question as to which 
species is the model and which the mimic need not cause any 
anxiety. In such cases the rarer species would always be 
adapted in external characters to the commoner one. "The infer- 
ence that H. Distanti is the model is therefore erroneous from 
the new point of view; and, in spite of its ‘‘ pseudo scent- 
gland,” I believe that we must regard it as the mimic of Z. 
Bremer. 
To bring the argument home to entomologists, I will once 
more venture to state the case numerically, with special refer- 
ence to the species under discussion, using Fritz Miiller’s 
own figures for this purpose. Let us suppose that at the time 
when L. Distanti and H. Bremert were quite distinct there 
existed in a certain area during one season 10,000 individuals 
of the latter and 2000 of the former. If, say, 1200 individuals 
of a nauseous species are necessary for the education of young 
birds, this number would in each case be sacrificed, and the 
total number of butterflies lost would be 2400. But if the 
two species were so much alike that their foes could not dis- 
tinguish them, then we should have what, from a mimetic 
point of view would be, as regards birds &c., only one species, 
consisting of 12,000 individuals, of which 1200 have to be 
sacrificed. Now the loss would in this case fall upon the 
species in the ratio of their numbers, viz. 5:1; so that #. 
Bremert would lose 1000 and #. Distanti 200 individuals. 
In the former state of affairs (before the resemblance) each 
species would have lost 1200; now £. Distantd gains 1000 
individuals by its resemblance and EH. Bremert only 200. 
The total number of individuals with which we started was 
10,000 of #. Bremert and 2000 of H. Distanti; so that the 
last species gains $453 or 4, and the first species 12}0> or only 
sy of its whole number. The advantage in favour of the 
rarer 17, Distanti, conferred upon it by its being mistaken for 
LH. Bremert, would thus be twenty-five times as great as the 
advantage which the commoner £. Bremerd derives from re- 
sembling H. Distant’. Surely in such a case the question as 
to which is the model does not admit of a doubt. 
This extension of the theory of mimicry, as far as I am 
able to see, makes no greater claim upon the credulity of 
naturalists than the older and more restricted view which made 
it essential that the model should always belong to a protected 
group, and the mimic to a family devoid of distasteful qualities. 
The factors concerned are in both cases the same—variation 
and natural selection; and the term “ mimicry” is as appli- 
cable to one class of cases as to the other. Mr. Distant, how- 
