86 
NATURAL SELECTION 
m 
either from below or else taking long strides up the funnel 
again. Mr. Butler has observed lizards fight with and finally 
devour humble bees, and a frog sitting on a bed of stone-crop 
leap up and catch the bees which flew over his head, and 
swallow them, in utter disregard of their stings. It is 
evident, therefore, that the possession of a disagreeable taste 
or odour is a more effectual protection to certain conspicuous 
caterpillars and moths than would be even the possession of 
a sting. 
The observations of these two gentlemen supply a very 
remarkable confirmation of the hypothetical solution of the diffi- 
culty which I had given two years before. And as it is generally 
acknowledged that the best test of the truth and complete- 
ness of a theory is the power which it gives us of prevision, 
we may, I think, fairly claim this as a ease in which the 
power of prevision has been successfully exerted, and therefore 
as furnishing a very powerful argument in favour of the 
truth of the theory of Natural Selection. 
Summary 
I have now completed a brief, and necessarily very im- 
perfect, survey of the various ways in which the external form 
and colouring of animals is adapted to be useful to them, 
either by concealing them from their enemies or from the 
creatures they prey upon. It has, I hope, been shown that 
the subject is one of much interest, both as regards a true com- 
prehension of the place each animal fills in the economy of 
nature, and the means by which it is enabled to maintain that 
place ; and also as teaching us how important a part is played 
by the minutest details in the structure of animals, and how 
complicated and delicate is the equilibrium of the organic 
world. 
My exposition of the subject having been necessarily 
somewhat lengthy and full of details, it will be as well to 
recapitulate its main points. 
There is a general harmony in nature between the colours 
of an animal and those of its habitation. Arctic animals are 
white, desert animals are sand -coloured; dwellers among 
leaves and grass are green; nocturnal animals are dusky. 
These colours are not universal, but are very general, and are 
