264 
DARWINISM 
CHAP. 
have a patch of bare black skin round the eyes, and a ruff 
of curious pale recurved feathers on the nape, whence their 
name of Friar-birds, the ruff being supposed to resemble the 
cowl of a friar. These peculiarities are imitated in the orioles 
by patches of feathers of corresponding colours; while the dif¬ 
ferent tints of the two species in each island are exactly the 
same. Thus in Bouru both are earthy brown ; in Ceram they are 
both washed with yellow ochre ; in Timor the under surface 
is pale and the throat nearly white, and Mr. H. 0. Forbes has 
recently discovered another pair in the island of Timor Laut. 
The close resemblance of these several pairs of birds, of widely 
different families, is quite comparable with that of many of the 
insects already described. It is so close that the preserved 
specimens have even deceived naturalists ; for, in the great 
French work, Voyage de VAstrolabe, the oriole of Bouru is 
actually described and figured as a honey-sucker; and Mr. 
Forbes tells us that, when his birds were submitted to Dr. 
Sclater for description, the oriole and the honey-sucker were, 
previous to close examination, considered to be the same 
species. 
Objections to the Theory of Mimicry. 
To set forth adequately the varied and surprising facts of 
mimicry would need a large and copiously illustrated volume; 
and no more interesting subject could be taken up by a 
naturalist who has access to our great collections and can de¬ 
vote the necessary time to search out the many examples of 
mimicry that lie hidden in our museums. The brief sketch of 
the subject that has been here given will, however, serve to 
indicate its nature, and to show the weakness of the objections 
that were at first made to it. It was urged that the action 
of “ like conditions,” with “ accidental resemblances ” and 
“ reversion to ancestral types,” would account for the facts. If, 
however, we consider the actual phenomena as here set forth, 
and the very constant conditions under which they occur, we 
shall see how utterly inadequate are these causes, either 
singly or combined. These constant conditions are —- 
1. That the imitative species occur in the same area and 
occupy the very same station as the imitated. 
2. That the imitators are always the more defenceless. 
