ITI PROTECTIVE RESEMBLANCES AMONG ANIMALS 47 
this insect belongs, is more or less imitative, and a great 
number of the species are called ‘‘ walking-stick insects,” from 
their singular resemblance to twigs and branches. Some of 
these are a foot long and as thick as one’s finger, and their 
whole colouring, form, rugosity, and the arrangement of the 
head, legs, and antennz are such as to render them absolutely 
identical in appearance with dead sticks. They hang loosely 
about shrubs in the forest, and have the extraordinary habit 
of stretching out their legs unsymmetrically, so as to render 
the deception more complete. One of these creatures ob- 
tained by myself in Borneo (Ceroxylus laceratus) was covered 
over with foliaceous excrescences of a clear olive green colour, 
so as exactly to resemble a stick grown over by a creeping 
moss or jungermannia. The Dyak who brought it me 
assured me it was grown over with moss although alive, and 
it was only after a most minute examination that I could 
convince myself it was not so. 
We need not adduce any more examples to show how 
important are the details of form and of colouring in animals, 
and that their very existence may often depend upon their 
being by these means concealed from their enemies. This 
kind of protection is found apparently in every class and 
order, for it has been noticed wherever we can obtain suffi- 
cient knowledge of the details of an animal’s life-history. It 
varies in degree, from the mere absence of conspicuous colour 
or a general harmony with the prevailing tints of nature, up 
to such a minute and detailed resemblance to inorganic or 
vegetable structures as to realise the talisman of the fairy 
tale, and to give its possessor the power of rendering itself 
invisible. 
Theory of Protective Colouring 
We will now endeavour to show how these wonderful 
resemblances have most probably been brought about. Re- 
turning to the higher animals, let us consider the remarkable 
fact of the rarity of white colouring in the mammalia or birds 
of the temperate or tropical zones in a state of nature. There 
is not a single white land-bird or quadruped in Europe, except 
the few arctic or alpine species, to which white is a protective 
colour. Yet in many of these creatures there seems to be no 
