90 NATURAL SELECTION III 
Conclusion 
Although such a store of interesting facts has been already 
accumulated, the subject we have been discussing is one of 
which comparatively little is really known. The natural 
history of the tropics has never yet been studied on the spot 
with a full appreciation of “what to observe” in this matter. 
The varied ways in which the colouring and form of animals 
serve for their protection, their strange disguises as vegetable 
or mineral substances, their wonderful mimicry of other 
beings, offer an almost unworked and inexhaustible field of 
discovery for the zoologist, and will assuredly throw much 
light on the laws and conditions which have resulted in the 
wonderful variety of colour, shade, and marking which con- 
stitutes one of the most pleasing characteristics of the animal 
world, but the immediate causes of which it has hitherto 
been most difficult to explain. 
If I have succeeded in showing that in this wide and 
picturesque domain of nature, results which have hitherto 
been supposed to depend either upon those incalculable com- 
binations of laws which we term chance or upon the direct 
volition of the Creator, are really due to the action of 
comparatively well-known and simple causes, I shall have 
attained my present purpose, which has been to extend the 
interest so generally felt in the more striking facts of natural 
history to a large class of curious but much neglected details ; 
and to further, in however slight a degree, our knowledge of 
the subjection of the phenomena of life to the Reign of Law. 
