MIMICRY IN EAST AFRICAN BUTTERFLIES 88 
pattern and are generally ornamented in the same way above 
and below. 
Now if a species is very abundant it can well bear the losses 
caused by this experimental tasting, but if it is a species of 
considerable rarity it is obvious that the losses so caused would 
be a very serious matter to it, for they will be in proportion 
not to its own numbers but to those of the young enemies who 
have to be educated up to recognising its peculiar character. 
Now, if such a rare species should come to resemble another 
distasteful species of great abundance so that its enemies are 
unable to distinguish the two, the losses will be shared and will 
be in proportion to the numbers of the two species, so that the 
losses which will fall on the rarer species will be comparatively 
few. Professor Poulton has argued very forcibly for the view 
that mimicry amongst butterflies belongs mainly to this last 
which is known as Mullerian mimicry in distinction from 
that recognised earlier which is known as Batesian mimicry. 
It is unnecessary to repeat all these arguments here, but it may 
be said that the ‘ mimics ’ are frequently anything but the 
scarce and hard-pressed species assumed by Bates, and indeed 
are frequently very dominant species indeed ; and one of the 
best-known African mimics — Hypolimnas misippus — in which 
the female alone is a mimic, not only accompanies its model 
throughout its immense range but has actually succeeded, 
in historic times, in invading South America and establishing 
itself in the most crowded area in the world without the 
presence of its model at all. 
It should be said there is a tendency amongst a considerable 
number of modern naturalists, particularly amongst those 
whose studies have been chiefly in connexion with the 
problems of heredity, to discredit the theories enunciated 
by Darwin and in particular the phenomena attributed 
to mimicry which yield them such powerful support. 
The phenomena which we have been considering are 
attributed to the uniform action of the same local conditions. 
These arguments have been met by Professor Poulton in the 
eighth chapter of his recent book ‘ Essays on Evolution.’ 
It is not desirable to enter into the numerous arguments and 
lines of investigation by which he shows that the theory of 
